jquery-validate v1.19.2 源码分析

一、代码主体结构

 二、源码分析

　　2.1  外层结构

　　

分析步骤

a. 简化结构如下

(function(param)｛

   　　 console.info(param);

　　}( "123" ));

　　执行结果：

　　123

　　立即执行函数

b. 根据步骤a即可理解外层结构的意思

    * 将封装的插件代码函数以参数的形式传入工厂方法, 函数内容根据环境探测结果采用不同方式执行，以兼容多种环境10     
     * 如果当前执行环境是amd｛Asynchronous Module Definition，即异步模块加载机制｝，则需要添加jquery依赖，回调函数 为传入的factory
     if ( typeof define === "function" && define.amd ) {
        define( ["jquery"], factory );
      }    
 
     * 如果当前环境是 CommonJS Modules , 则如下方式引入依赖执行factory
     if (typeof module === "object" && module.exports) {
        module.exports = factory( require( "jquery" ) );
    }
   
     * 其他普通浏览器环境直接执行函数
      factory(jQuery);
     

 2.2  $.validator 的定义

    

　　分析步骤

　　a. 简化结构如下

// 定义构造函数
$.validator = function( options, form ) {
    // do init method...
};

// 扩展 $.validator 函数属性，包括原型对象
$.extend( $.validator, {
    prop: value,
    prototype: {
        prop: value
    }
    // ... other props
});

　　b.构造函数逻辑代码

$.validator = function( options, form ) {
    // 对当前对象的配置赋值 = 将{}, 默认配置，自定义配置 合并到目标对象 settings 
    this.settings = $.extend( true, {}, $.validator.defaults, options );
    // 对当前的form赋值
    this.currentForm = form;
    // 初始化当前表单的 validator对象
    this.init();
};

　

　　c. 分析$.validator 函数 扩展的属性

// 默认配置，可自定义修改
defaults: {
        // 提示消息
        messages: {},
        // 分组
        groups: {},
        // 自定义校验规则
        rules: {},
        // 错误提示的类样式
        errorClass: "error",
        // 等待的类样式 
        pendingClass: "pending",
        // 有效的类样式
        validClass: "valid",
        // 错误提示的元素
        errorElement: "label",
        // xx
        focusCleanup: false,
        // xx
        focusInvalid: true,
        // xx 
        errorContainer: $( [] ),
        // xx
        errorLabelContainer: $( [] ),
        // 提交事件之前校验规则 
        onsubmit: true,
        // 忽略hidden属性
        ignore: ":hidden",
        // 默认忽略title的校验
        ignoreTitle: false,
        
        // 聚焦，当 focusCleanup 为true时，取消错误高亮效果
        onfocusin: function( element ) {
            this.lastActive = element;

            // Hide error label and remove error class on focus if enabled
            if ( this.settings.focusCleanup ) {
                if ( this.settings.unhighlight ) {
                    this.settings.unhighlight.call( this, element, this.settings.errorClass, this.settings.validClass );
                }
                this.hideThese( this.errorsFor( element ) );
            }
        },
        
        // 失去焦点 校验元素
        onfocusout: function( element ) {
            if ( !this.checkable( element ) && ( element.name in this.submitted || !this.optional( element ) ) ) {
                this.element( element );
            }
        },
        
        // 检查键盘事件，是否触发提交 
        onkeyup: function( element, event ) {

            // Avoid revalidate the field when pressing one of the following keys
            // Shift       => 16
            // Ctrl        => 17
            // Alt         => 18
            // Caps lock   => 20
            // End         => 35
            // Home        => 36
            // Left arrow  => 37
            // Up arrow    => 38
            // Right arrow => 39
            // Down arrow  => 40
            // Insert      => 45
            // Num lock    => 144
            // AltGr key   => 225
            var excludedKeys = [
                16, 17, 18, 20, 35, 36, 37,
                38, 39, 40, 45, 144, 225
            ];

            if ( event.which === 9 && this.elementValue( element ) === "" || $.inArray( event.keyCode, excludedKeys ) !== -1 ) {
                return;
            } else if ( element.name in this.submitted || element.name in this.invalid ) {
                this.element( element );
            }
        },
        
        // selects, radio, checkbox , 其他方式的option 元素的 点击事件
        onclick: function( element ) {
            
            // Click on selects, radiobuttons and checkboxes
            if ( element.name in this.submitted ) {
                this.element( element );

            // Or option elements, check parent select in that case
            } else if ( element.parentNode.name in this.submitted ) {
                this.element( element.parentNode );
            }
        },
        // 高亮效果
        highlight: function( element, errorClass, validClass ) {
            if ( element.type === "radio" ) {
                this.findByName( element.name ).addClass( errorClass ).removeClass( validClass );
            } else {
                $( element ).addClass( errorClass ).removeClass( validClass );
            }
        },
        
        // 取消高亮效果
        unhighlight: function( element, errorClass, validClass ) {
            if ( element.type === "radio" ) {
                this.findByName( element.name ).removeClass( errorClass ).addClass( validClass );
            } else {
                $( element ).removeClass( errorClass ).addClass( validClass );
            }
        }
}

    // 修改掉 $.validator.defaults 默认配置
    setDefaults: function( settings ) {
        $.extend( $.validator.defaults, settings );
    },
    
    // 类规则设置
    classRuleSettings: {
        required: { required: true },
        email: { email: true },
        url: { url: true },
        date: { date: true },
        dateISO: { dateISO: true },
        number: { number: true }, // 包含小数
        digits: { digits: true }, // 数字
        creditcard: { creditcard: true }
    },
    
    // 默认的规则提示
    messages: {
        required: "This field is required.",
        remote: "Please fix this field.",
        email: "Please enter a valid email address.",
        url: "Please enter a valid URL.",
        date: "Please enter a valid date.",
        dateISO: "Please enter a valid date (ISO).",
        number: "Please enter a valid number.",
        digits: "Please enter only digits.",
        equalTo: "Please enter the same value again.",
        maxlength: $.validator.format( "Please enter no more than {0} characters." ),
        minlength: $.validator.format( "Please enter at least {0} characters." ),
        rangelength: $.validator.format( "Please enter a value between {0} and {1} characters long." ),
        range: $.validator.format( "Please enter a value between {0} and {1}." ),
        max: $.validator.format( "Please enter a value less than or equal to {0}." ),
        min: $.validator.format( "Please enter a value greater than or equal to {0}." ),
        step: $.validator.format( "Please enter a multiple of {0}." )
    },

    // 自动创建范围 : false
    autoCreateRanges: false,

    //原型函数分析
    
    // 检验提示错误，错误列表大小
    size: function() {
        return this.errorList.length;
    },
    
    // 当前大小 = 0， 校验通过
    valid: function() {
        return this.size() === 0;
    }
    
    // 校验错误的个数
    numberOfInvalids: function() {
        return this.objectLength( this.invalid );
    },
    
    // 返回传入对象长度
    objectLength: function( obj ) {
        /* jshint unused: false */
        var count = 0,
            i;
        for ( i in obj ) {
    
            // This check allows counting elements with empty error
            // message as invalid elements
            if ( obj[ i ] !== undefined && obj[ i ] !== null && obj[ i ] !== false ) {
                count++;
            }
        }
        return count;
    },
    
    // 聚焦到最后一个错误提示的元素
    focusInvalid: function() {
        if ( this.settings.focusInvalid ) {
            try {
                $( this.findLastActive() || this.errorList.length && this.errorList[ 0 ].element || [] )
                .filter( ":visible" )
                .trigger( "focus" )
    
                // Manually trigger focusin event; without it, focusin handler isn't called, findLastActive won't have anything to find
                .trigger( "focusin" );
            } catch ( e ) {
    
                // Ignore IE throwing errors when focusing hidden elements
            }
        }
    },
    
    // 查找最后一个元素active
    findLastActive: function() {
        var lastActive = this.lastActive;
        return lastActive && $.grep( this.errorList, function( n ) {
            return n.element.name === lastActive.name;
        } ).length === 1 && lastActive;
    },

// xx
    clean: function( selector ) {
        return $( selector )[ 0 ];
    },
    
    // 错误样式 
    errors: function() {
        var errorClass = this.settings.errorClass.split( " " ).join( "." );
        return $( this.settings.errorElement + "." + errorClass, this.errorContext );
    },
    
    // 重置 
    resetInternals: function() {
        this.successList = [];
        this.errorList = [];
        this.errorMap = {};
        this.toShow = $( [] );
        this.toHide = $( [] );
    },
    
    // 重置
    reset: function() {
        this.resetInternals();
        this.currentElements = $( [] );
    },
    
    // form 准备
    prepareForm: function() {
        this.reset();
        this.toHide = this.errors().add( this.containers );
    },
    
    // 元素准备
    prepareElement: function( element ) {
        this.reset();
        this.toHide = this.errorsFor( element );
    },
    
    //  从错误列表里过滤出元素
    errorsFor: function( element ) {
        var name = this.escapeCssMeta( this.idOrName( element ) ),
            describer = $( element ).attr( "aria-describedby" ),
            selector = "label[for='" + name + "'], label[for='" + name + "'] *";
    
        // 'aria-describedby' should directly reference the error element
        if ( describer ) {
            selector = selector + ", #" + this.escapeCssMeta( describer )
                .replace( /s+/g, ", #" );
        }
        
        // [1,23,3].filter( function(i ) { return  i == 23;}); // 从数组中过滤
        
        return this
            .errors()
            .filter( selector );
    },
    
    // 正则替换字符串返回结果
    escapeCssMeta: function( string ) {
        return string.replace( /([\!"#$%&'()*+,./:;<=>?@[]^`{|}~])/g, "\$1" );
    },
    
    // 获取元素的id或name值
    idOrName: function( element ) {
        return this.groups[ element.name ] || ( this.checkable( element ) ? element.name : element.id || element.name );
    },

    // 返回元素的message【自定义或默认】
    customDataMessage: function( element, method ) {
        return $( element ).data( "msg" + method.charAt( 0 ).toUpperCase() +
            method.substring( 1 ).toLowerCase() ) || $( element ).data( "msg" );
    },
    
    // 通过名称读取message
    customMessage: function( name, method ) {
        var m = this.settings.messages[ name ];
        return m && ( m.constructor === String ? m : m[ method ] );
    },
    
    // 返回第一个非undefined的参数值
    findDefined: function() {
        for ( var i = 0; i < arguments.length; i++ ) {
            if ( arguments[ i ] !== undefined ) {
                return arguments[ i ];
            }
        }
        return undefined;
    },
    
    // The second parameter 'rule' used to be a string, and extended to an object literal
    // of the following form:
    // rule = {
    //     method: "method name",
    //     parameters: "the given method parameters"
    // }
    // 现在还支持老的行为(rule == string)，下一个版本没了
    // The old behavior still supported, kept to maintain backward compatibility with
    // old code, and will be removed in the next major release. ; 
    defaultMessage: function( element, rule ) {
        if ( typeof rule === "string" ) {
            rule = { method: rule };
        }
        // 按次序读取message，直到找到一个非undefined的message
        var message = this.findDefined(
                this.customMessage( element.name, rule.method ),
                this.customDataMessage( element, rule.method ),
    
                // 'title' is never undefined, so handle empty string as undefined
                !this.settings.ignoreTitle && element.title || undefined,
                $.validator.messages[ rule.method ],
                "<strong>Warning: No message defined for " + element.name + "</strong>"
            ),
            theregex = /$?{(d+)}/g;
        if ( typeof message === "function" ) {
            message = message.call( this, rule.parameters, element );
        } else if ( theregex.test( message ) ) {
            message = $.validator.format( message.replace( theregex, "{$1}" ), rule.parameters );
        }
    
        return message;
    },
    
    // 通过元素和规则格式化message，放到错误列表
    formatAndAdd: function( element, rule ) {
        var message = this.defaultMessage( element, rule );
    
        this.errorList.push( {
            message: message,
            element: element,
            method: rule.method
        } );
    
        this.errorMap[ element.name ] = message;
        this.submitted[ element.name ] = message;
    },
    
    // 检查是否有包裹层
    addWrapper: function( toToggle ) {
        if ( this.settings.wrapper ) {
            toToggle = toToggle.add( toToggle.parent( this.settings.wrapper ) );
        }
        return toToggle;
    },
    
    // 显示错误提示 
    defaultShowErrors: function() {
        var i, elements, error;
        // 迭代errorlist，显示错误提示
        for ( i = 0; this.errorList[ i ]; i++ ) {
            error = this.errorList[ i ];
            if ( this.settings.highlight ) {
                this.settings.highlight.call( this, error.element, this.settings.errorClass, this.settings.validClass );
            }
            this.showLabel( error.element, error.message );
        }
        
        // 如果错误个数大于0 ; xx
        if ( this.errorList.length ) {
            this.toShow = this.toShow.add( this.containers );
        }
        
        // 如果setting.success 为true，显示正常校验的提示
        if ( this.settings.success ) {
            for ( i = 0; this.successList[ i ]; i++ ) {
                this.showLabel( this.successList[ i ] );
            }
        }
        
        // 校验通过的元素取消高亮效果
        if ( this.settings.unhighlight ) {
            for ( i = 0, elements = this.validElements(); elements[ i ]; i++ ) {
                this.settings.unhighlight.call( this, elements[ i ], this.settings.errorClass, this.settings.validClass );
            }
        }
        
        //  $([11,2,3]).not([2,3]); console.info(a.toArray());
        this.toHide = this.toHide.not( this.toShow );
        
        // xx
        this.hideErrors();
        
        // xx
        this.addWrapper( this.toShow ).show();
    },
    
    showLabel: function( element, message ) {
        var place, group, errorID, v,
            error = this.errorsFor( element ),
            elementID = this.idOrName( element ),
            describedBy = $( element ).attr( "aria-describedby" );
    
        if ( error.length ) {
    
            // Refresh error/success class 干掉有效的样式添加错误提示的样式
            error.removeClass( this.settings.validClass ).addClass( this.settings.errorClass );
    
            // Replace message on existing label 替换错误提示
            error.html( message );
        } else {
    
            // Create error element 创建错误提示元素
            error = $( "<" + this.settings.errorElement + ">" )
                .attr( "id", elementID + "-error" )
                .addClass( this.settings.errorClass )
                .html( message || "" );
    
            // Maintain reference to the element to be placed into the DOM
            place = error;
            if ( this.settings.wrapper ) {
    
                // Make sure the element is visible, even in IE
                // actually showing the wrapped element is handled elsewhere
                place = error.hide().show().wrap( "<" + this.settings.wrapper + "/>" ).parent();
            }
            
            // 插入提示文本
            if ( this.labelContainer.length ) {
                this.labelContainer.append( place );
            } else if ( this.settings.errorPlacement ) {
                // 自定义 错误替换 函数
                this.settings.errorPlacement.call( this, place, $( element ) );
            } else {
                place.insertAfter( element );
            }
    
            // link 错误到元素
            if ( error.is( "label" ) ) {
    
                // If the error is a label, then associate using 'for'
                error.attr( "for", elementID );
    
                // If the element is not a child of an associated label, then it's necessary
                // to explicitly apply aria-describedby
            } else if ( error.parents( "label[for='" + this.escapeCssMeta( elementID ) + "']" ).length === 0 ) {
                errorID = error.attr( "id" );
    
                // Respect existing non-error aria-describedby
                if ( !describedBy ) {
                    describedBy = errorID;
                } else if ( !describedBy.match( new RegExp( "\b" + this.escapeCssMeta( errorID ) + "\b" ) ) ) {
    
                    // Add to end of list if not already present
                    describedBy += " " + errorID;
                }
                $( element ).attr( "aria-describedby", describedBy );
    
                // If this element is grouped, then assign to all elements in the same group
                group = this.groups[ element.name ];
                if ( group ) {
                    v = this;
                    $.each( v.groups, function( name, testgroup ) {
                        if ( testgroup === group ) {
                            $( "[name='" + v.escapeCssMeta( name ) + "']", v.currentForm )
                                .attr( "aria-describedby", error.attr( "id" ) );
                        }
                    } );
                }
            }
        }
        // 定义success的时候，
        if ( !message && this.settings.success ) {
            error.text( "" );
            if ( typeof this.settings.success === "string" ) {
                // string时 添加样式 
                error.addClass( this.settings.success );
            } else {
                // function时，调用函数
                this.settings.success( error, element );
            }
        }
        this.toShow = this.toShow.add( error );
    },

        // 从当前元素中去掉校验不通过的元素
        validElements: function() {
            return this.currentElements.not( this.invalidElements() );
        },
        
        // 从errorList中返回 校验不通过的元素集合
        invalidElements: function() {
            return $( this.errorList ).map( function() {
                return this.element;
            } );
        },

        // 校验目标 
        validationTargetFor: function( element ) {

            // If radio/checkbox, validate first element in group instead 如果元素是radio,checkbox；查找组
            if ( this.checkable( element ) ) {
                element = this.findByName( element.name );
            }

            // Always apply ignore filter
            return $( element ).not( this.settings.ignore )[ 0 ];
        },

        // 检查是否是radio或checkbox
        checkable: function( element ) {
            return ( /radio|checkbox/i ).test( element.type );
        },

        // 表单元素查找
        findByName: function( name ) {
            return $( this.currentForm ).find( "[name='" + this.escapeCssMeta( name ) + "']" );
        },
        
        // 获取元素节点的长度
        getLength: function( value, element ) {
            switch ( element.nodeName.toLowerCase() ) {
            case "select":
                // 下拉
                return $( "option:selected", element ).length;
            case "input":
                if ( this.checkable( element ) ) { 
                    // radio checkbox
                    return this.findByName( element.name ).filter( ":checked" ).length;
                }
            }
            // 普通的表单
            return value.length;
        },

        // 
        depend: function( param, element ) {
            return this.dependTypes[ typeof param ] ? this.dependTypes[ typeof param ]( param, element ) : true;
        },
        
        // 类型依赖    
        dependTypes: {
            "boolean": function( param ) {
                return param;
            },
            "string": function( param, element ) {
                return !!$( param, element.form ).length;
            },
            "function": function( param, element ) {
                return param( element );
            }
        },

        // 非必填项 
        optional: function( element ) {
            var val = this.elementValue( element );
            return !$.validator.methods.required.call( this, val, element ) && "dependency-mismatch";
        },

        // 构建errorlist和successlist 调用函数显示错误label
        showErrors: function( errors ) {
            if ( errors ) {
                var validator = this;
        
                // Add items to error list and map
                $.extend( this.errorMap, errors );
                this.errorList = $.map( this.errorMap, function( message, name ) {
                    return {
                        message: message,
                        element: validator.findByName( name )[ 0 ]
                    };
                } );
        
                // Remove items from success list
                this.successList = $.grep( this.successList, function( element ) {
                    return !( element.name in errors );
                } );
            }
            if ( this.settings.showErrors ) {
                this.settings.showErrors.call( this, this.errorMap, this.errorList );
            } else {
                this.defaultShowErrors();
            }
        },
        
        // 检测$.fn.resetForm 是否存在
        resetForm: function() {
            if ( $.fn.resetForm ) {
                $( this.currentForm ).resetForm();
            }
            this.invalid = {};
            this.submitted = {};
            this.prepareForm();
            this.hideErrors();
            var elements = this.elements()
                .removeData( "previousValue" )
                .removeAttr( "aria-invalid" );
            
            this.resetElements( elements );
        },
        
        // 重置元素提示样式
        resetElements: function( elements ) {
            var i;
        
            if ( this.settings.unhighlight ) {
                for ( i = 0; elements[ i ]; i++ ) {
                    this.settings.unhighlight.call( this, elements[ i ],
                        this.settings.errorClass, "" );
                    this.findByName( elements[ i ].name ).removeClass( this.settings.validClass );
                }
            } else {
                elements
                    .removeClass( this.settings.errorClass )
                    .removeClass( this.settings.validClass );
            }
        },
        
        // 隐藏错误
        hideErrors: function() {
            this.hideThese( this.toHide );
        },
        
        // xx
        hideThese: function( errors ) {
            errors.not( this.containers ).text( "" );
            this.addWrapper( errors ).hide();
        },

// 规范化所有规则
        normalizeRules: function( rules, element ) {
            
            // 迭代rules
            $.each( rules, function( prop, val ) {
        
                // 当规则值为false，非必填项，规则去除
                if ( val === false ) {
                    delete rules[ prop ];
                    return;
                }
                // 检查参数是否是否有依赖
                if ( val.param || val.depends ) {
                    var keepRule = true;
                    switch ( typeof val.depends ) {
                    case "string":
                        keepRule = !!$( val.depends, element.form ).length;
                        break;
                    case "function":
                        keepRule = val.depends.call( element, element );
                        break;
                    }
                    // 规则有效用规则，规则无效删除规则
                    if ( keepRule ) {
                        rules[ prop ] = val.param !== undefined ? val.param : true;
                    } else {
                        $.data( element.form, "validator" ).resetElements( $( element ) );
                        delete rules[ prop ];
                    }
                }
            } );
        
            // Evaluate parameters
            $.each( rules, function( rule, parameter ) {
                rules[ rule ] = $.isFunction( parameter ) && rule !== "normalizer" ? parameter( element ) : parameter;
            } );
        
            // 格式化数字 最大长度，最小长度
            $.each( [ "minlength", "maxlength" ], function() {
                if ( rules[ this ] ) {
                    rules[ this ] = Number( rules[ this ] );
                }
            } );
            
            // 范围规则
            $.each( [ "rangelength", "range" ], function() {
                var parts;
                if ( rules[ this ] ) {
                    if ( $.isArray( rules[ this ] ) ) {
                        rules[ this ] = [ Number( rules[ this ][ 0 ] ), Number( rules[ this ][ 1 ] ) ];
                    } else if ( typeof rules[ this ] === "string" ) {
                        parts = rules[ this ].replace( /[[]]/g, "" ).split( /[s,]+/ );
                        rules[ this ] = [ Number( parts[ 0 ] ), Number( parts[ 1 ] ) ];
                    }
                }
            } );
        
            // 是否自动创建范围规则, 是： 删除大小规则，创建范围规则
            if ( $.validator.autoCreateRanges ) {
        
                // Auto-create ranges
                if ( rules.min != null && rules.max != null ) {
                    rules.range = [ rules.min, rules.max ];
                    delete rules.min;
                    delete rules.max;
                }
                if ( rules.minlength != null && rules.maxlength != null ) {
                    rules.rangelength = [ rules.minlength, rules.maxlength ];
                    delete rules.minlength;
                    delete rules.maxlength;
                }
            }
        
            return rules;
        },
        
        // 规范化rule, e.g., "required" to {required:true}
        normalizeRule: function( data ) {
            if ( typeof data === "string" ) {
                var transformed = {};
                $.each( data.split( /s/ ), function() {
                    transformed[ this ] = true;
                } );
                data = transformed;
            }
            return data;
        },
        
        // 元素
        element: function( element ) {
            var cleanElement = this.clean( element ),
                checkElement = this.validationTargetFor( cleanElement ),
                v = this,
                result = true,
                rs, group;
            
            if ( checkElement === undefined ) {
                delete this.invalid[ cleanElement.name ];
            } else {
                this.prepareElement( checkElement );
                this.currentElements = $( checkElement );

                // If this element is grouped, then validate all group elements already
                // containing a value
                group = this.groups[ checkElement.name ];
                if ( group ) {
                    $.each( this.groups, function( name, testgroup ) {
                        if ( testgroup === group && name !== checkElement.name ) {
                            cleanElement = v.validationTargetFor( v.clean( v.findByName( name ) ) );
                            if ( cleanElement && cleanElement.name in v.invalid ) {
                                v.currentElements.push( cleanElement );
                                result = v.check( cleanElement ) && result;
                            }
                        }
                    } );
                }

                rs = this.check( checkElement ) !== false;
                result = result && rs;
                if ( rs ) {
                    this.invalid[ checkElement.name ] = false;
                } else {
                    this.invalid[ checkElement.name ] = true;
                }

                if ( !this.numberOfInvalids() ) {

                    // Hide error containers on last error
                    this.toHide = this.toHide.add( this.containers );
                }
                this.showErrors();

                // Add aria-invalid status for screen readers
                $( element ).attr( "aria-invalid", !rs );
            }

            return result;
        },
        
        // 迭代表单元素
        elements: function() {
            var validator = this,
                rulesCache = {};

            // 查找通过的元素不包含submit和reset按纽, image,dissabled, 校验外元素
            return $( this.currentForm )
            .find( "input, select, textarea, [contenteditable]" )
            .not( ":submit, :reset, :image, :disabled" )
            .not( this.settings.ignore )
            .filter( function() {
                var name = this.name || $( this ).attr( "name" ); // For contenteditable
                var isContentEditable = typeof $( this ).attr( "contenteditable" ) !== "undefined" && $( this ).attr( "contenteditable" ) !== "false";

                if ( !name && validator.settings.debug && window.console ) {
                    console.error( "%o has no name assigned", this );
                }

                // Set form expando on contenteditable
                if ( isContentEditable ) {
                    // 找到当前元素的最接近的父节点form元素
                    this.form = $( this ).closest( "form" )[ 0 ];
                    this.name = name;
                }

                // Ignore elements that belong to other/nested forms
                if ( this.form !== validator.currentForm ) {
                    return false;
                }

                // Select only the first element for each name, and only those with rules specified
                if ( name in rulesCache || !validator.objectLength( $( this ).rules() ) ) {
                    return false;
                }

                rulesCache[ name ] = true;
                return true;
            } );
        },

        elementValue: function( element ) {
            var $element = $( element ),
                type = element.type,
                isContentEditable = typeof $element.attr( "contenteditable" ) !== "undefined" && $element.attr( "contenteditable" ) !== "false",
                val, idx;

            if ( type === "radio" || type === "checkbox" ) {
                // radio或checkbox
                return this.findByName( element.name ).filter( ":checked" ).val();
            } else if ( type === "number" && typeof element.validity !== "undefined" ) {
                // 数字的情况下，返回元素的值是否正确
                return element.validity.badInput ? "NaN" : $element.val();
            }

            if ( isContentEditable ) {
                // 文本编辑器 获取文本内容 text
                val = $element.text();
            } else {
                // 获取元素值
                val = $element.val();
            }
            
            // 文件类型，获取文件名，读取文件最后一个/
            if ( type === "file" ) {

                // Modern browser (chrome & safari)
                if ( val.substr( 0, 12 ) === "C:\fakepath\" ) {
                    return val.substr( 12 );
                }

                // Legacy browsers
                // Unix-based path
                idx = val.lastIndexOf( "/" );
                if ( idx >= 0 ) {
                    return val.substr( idx + 1 );
                }

                // Windows-based path
                idx = val.lastIndexOf( "\" );
                if ( idx >= 0 ) {
                    return val.substr( idx + 1 );
                }

                // Just the file name
                return val;
            }
            
            // 如果是字符串类型，去掉回车符
            if ( typeof val === "string" ) {
                return val.replace( /
/g, "" );
            }
            return val;
        },
        
        validationTargetFor: function( element ) {
            // If radio/checkbox, validate first element in group instead
            if ( this.checkable( element ) ) {
                element = this.findByName( element.name );
            }
            // Always apply ignore filter
            return $( element ).not( this.settings.ignore )[ 0 ];
        },
        
        // 检查 校验元素
        check: function( element ) {
            element = this.validationTargetFor( this.clean( element ) );

            var rules = $( element ).rules(),
                rulesCount = $.map( rules, function( n, i ) {
                    return i;
                } ).length,
                dependencyMismatch = false,
                val = this.elementValue( element ),
                result, method, rule, normalizer;

            // Prioritize the local normalizer defined for this element over the global one
            // if the former exists, otherwise user the global one in case it exists.
            if ( typeof rules.normalizer === "function" ) {
                normalizer = rules.normalizer;
            } else if (    typeof this.settings.normalizer === "function" ) {
                normalizer = this.settings.normalizer;
            }

            // If normalizer is defined, then call it to retreive the changed value instead
            // of using the real one.
            // Note that `this` in the normalizer is `element`.
            if ( normalizer ) {
                val = normalizer.call( element, val );

                // Delete the normalizer from rules to avoid treating it as a pre-defined method.
                delete rules.normalizer;
            }

            for ( method in rules ) {
                rule = { method: method, parameters: rules[ method ] };
                try {
                    // 重要
                    result = $.validator.methods[ method ].call( this, val, element, rule.parameters );

                    // If a method indicates that the field is optional and therefore valid,
                    // don't mark it as valid when there are no other rules
                    if ( result === "dependency-mismatch" && rulesCount === 1 ) {
                        dependencyMismatch = true;
                        continue;
                    }
                    dependencyMismatch = false;

                    if ( result === "pending" ) {
                        this.toHide = this.toHide.not( this.errorsFor( element ) );
                        return;
                    }

                    if ( !result ) {
                        this.formatAndAdd( element, rule );
                        return false;
                    }
                } catch ( e ) {
                    if ( this.settings.debug && window.console ) {
                        console.log( "Exception occurred when checking element " + element.id + ", check the '" + rule.method + "' method.", e );
                    }
                    if ( e instanceof TypeError ) {
                        e.message += ".  Exception occurred when checking element " + element.id + ", check the '" + rule.method + "' method.";
                    }

                    throw e;
                }
            }
            if ( dependencyMismatch ) {
                return;
            }
            if ( this.objectLength( rules ) ) {
                this.successList.push( element );
            }
            return true;
        },

        form: function() {
            this.checkForm();
            $.extend( this.submitted, this.errorMap );
            this.invalid = $.extend( {}, this.errorMap );
            if ( !this.valid() ) {
                $( this.currentForm ).triggerHandler( "invalid-form", [ this ] );
            }
            this.showErrors();
            return this.valid();
        },
        
        // 校验form表单所有元素，获取校验结果 当 this.valid()> 0的时候，表示当前的form表单校验不通过
        checkForm: function() {
            this.prepareForm();
            for ( var i = 0, elements = ( this.currentElements = this.elements() ); elements[ i ]; i++ ) {
                this.check( elements[ i ] );
            }
            return this.valid();
        },
        
        // 旧值
        previousValue: function( element, method ) {
            method = typeof method === "string" && method || "remote";
        
            return $.data( element, "previousValue" ) || $.data( element, "previousValue", {
                old: null,
                valid: true,
                message: this.defaultMessage( element, { method: method } )
            } );
        },
        
        // Cleans up all forms and elements, removes validator-specific events 重置
        destroy: function() {
            this.resetForm();
        
            $( this.currentForm )
                .off( ".validate" )
                .removeData( "validator" )
                .find( ".validate-equalTo-blur" )
                    .off( ".validate-equalTo" )
                    .removeClass( "validate-equalTo-blur" )
                .find( ".validate-lessThan-blur" )
                    .off( ".validate-lessThan" )
                    .removeClass( "validate-lessThan-blur" )
                .find( ".validate-lessThanEqual-blur" )
                    .off( ".validate-lessThanEqual" )
                    .removeClass( "validate-lessThanEqual-blur" )
                .find( ".validate-greaterThanEqual-blur" )
                    .off( ".validate-greaterThanEqual" )
                    .removeClass( "validate-greaterThanEqual-blur" )
                .find( ".validate-greaterThan-blur" )
                    .off( ".validate-greaterThan" )
                    .removeClass( "validate-greaterThan-blur" );
        }

init: function() {
    this.labelContainer = $(this.settings.errorLabelContainer);
    this.errorContext = this.labelContainer.length && this.labelContainer || $(this.currentForm);
    this.containers = $(this.settings.errorContainer).add(this.settings.errorLabelContainer);
    this.submitted = {};
    this.valueCache = {};
    this.pendingRequest = 0;
    this.pending = {};
    this.invalid = {};
    this.reset();

    var currentForm = this.currentForm,
        groups = (this.groups = {}),
        rules;
    $.each(this.settings.groups, function(key, value) {
        if (typeof value === "string") {
            value = value.split(/s/);
        }
        $.each(value, function(index, name) {
            groups[name] = key;
        });
    });
    
    // 格式化规则
    rules = this.settings.rules;
    $.each(rules, function(key, value) {
        rules[key] = $.validator.normalizeRule(value);
    });
    
    // 事件绑定
    function delegate(event) {
        var isContentEditable = typeof $(this).attr("contenteditable") !== "undefined" && $(this).attr("contenteditable") !==
            "false";

        // Set form expando on contenteditable
        if (!this.form && isContentEditable) {
            this.form = $(this).closest("form")[0];
            this.name = $(this).attr("name");
        }

        // Ignore the element if it belongs to another form. This will happen mainly
        // when setting the `form` attribute of an input to the id of another form.
        if (currentForm !== this.form) {
            return;
        }

        var validator = $.data(this.form, "validator"),
        // 如：onfocusin ， 查看onfocusin实现逻辑
            eventType = "on" + event.type.replace(/^validate/, ""),
            settings = validator.settings;
        if (settings[eventType] && !$(this).is(settings.ignore)) {
            settings[eventType].call(validator, this, event);
        }
    }
    
    // 给未来的元素[ [type=xx]表单元素 ] 绑定事件 onfocusin, onfocusout , onkeyup
    $(this.currentForm)
        .on("focusin.validate focusout.validate keyup.validate",
            ":text, [type='password'], [type='file'], select, textarea, [type='number'], [type='search'], " +
            "[type='tel'], [type='url'], [type='email'], [type='datetime'], [type='date'], [type='month'], " +
            "[type='week'], [type='time'], [type='datetime-local'], [type='range'], [type='color'], " +
            "[type='radio'], [type='checkbox'], [contenteditable], [type='button']" delegate)

        // Support: Chrome, oldIE
        // "select" is provided as event.target when clicking a option 兼容IE，chrome，绑定click, select事件
        .on("click.validate", "select, option, [type='radio'], [type='checkbox']", delegate);

    if (this.settings.invalidHandler) {
        $(this.currentForm).on("invalid-form.validate", this.settings.invalidHandler);
    }
}

　　d. 默认的校验规则函数

// 规则校验函数

        check: function(){
                ...
                result = $.validator.methods[ method ].call( this, val, element, rule.parameters );
                ...
        }
        
         
        // https://jqueryvalidation.org/jQuery.validator.methods/
        methods: {
            
            // required 校验规则
            required: function( value, element, param ) {
        
                // Check if dependency is met    
                if ( !this.depend( param, element ) ) {
                    return "dependency-mismatch";
                }
                // 检查元素节点是否是select
                if ( element.nodeName.toLowerCase() === "select" ) {
        
                    // Could be an array for select-multiple or a string, both are fine this way
                    var val = $( element ).val();
                    // 已选中至少一个值， 且值长度大于0
                    return val && val.length > 0;
                }
                // 检查元素是否是checkable[radio,checkbox]元素 至少一个值
                if ( this.checkable( element ) ) {
                    return this.getLength( value, element ) > 0;
                }
                // 检查元素值存在，且值长度大于0
                return value !== undefined && value !== null && value.length > 0;
            },
        
            // email  校验规则
            email: function( value, element ) {    
        
                // From https://html.spec.whatwg.org/multipage/forms.html#valid-e-mail-address
                // Retrieved 2014-01-14 
                // If you have a problem with this implementation, report a bug against the above spec
                // Or use custom methods to implement your own email validation
                return this.optional( element ) || /^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$/.test( value );
            },
        
            // url校验规则
            url: function( value, element ) {
        
                // Copyright (c) 2010-2013 Diego Perini, MIT licensed
                // https://gist.github.com/dperini/729294
                // see also https://mathiasbynens.be/demo/url-regex
                // modified to allow protocol-relative URLs
                return this.optional( element ) || /^(?:(?:(?:https?|ftp):)?//)(?:S+(?::S*)?@)?(?:(?!(?:10|127)(?:.d{1,3}){3})(?!(?:169.254|192.168)(?:.d{1,3}){2})(?!172.(?:1[6-9]|2d|3[0-1])(?:.d{1,3}){2})(?:[1-9]d?|1dd|2[01]d|22[0-3])(?:.(?:1?d{1,2}|2[0-4]d|25[0-5])){2}(?:.(?:[1-9]d?|1dd|2[0-4]d|25[0-4]))|(?:(?:[a-zu00a1-uffff0-9]-*)*[a-zu00a1-uffff0-9]+)(?:.(?:[a-zu00a1-uffff0-9]-*)*[a-zu00a1-uffff0-9]+)*(?:.(?:[a-zu00a1-uffff]{2,})).?)(?::d{2,5})?(?:[/?#]S*)?$/i.test( value );
            },
        
            // 日期规则
            date: ( function() {
                var called = false;
        
                return function( value, element ) {
                    if ( !called ) {
                        called = true;
                        if ( this.settings.debug && window.console ) {
                            console.warn(
                                "The `date` method is deprecated and will be removed in version '2.0.0'.
" +
                                "Please don't use it, since it relies on the Date constructor, which
" +
                                "behaves very differently across browsers and locales. Use `dateISO`
" +
                                "instead or one of the locale specific methods in `localizations/`
" +
                                "and `additional-methods.js`."
                            );
                        }
                    }
        
                    return this.optional( element ) || !/Invalid|NaN/.test( new Date( value ).toString() );
                };
            }() ),
        
            // https://jqueryvalidation.org/dateISO-method/
            dateISO: function( value, element ) {
                return this.optional( element ) || /^d{4}[/-](0?[1-9]|1[012])[/-](0?[1-9]|[12][0-9]|3[01])$/.test( value );
            },
        
            // 数字 包括小数
            number: function( value, element ) {
                return this.optional( element ) || /^(?:-?d+|-?d{1,3}(?:,d{3})+)?(?:.d+)?$/.test( value );
            },
        
            // 整数
            digits: function( value, element ) {
                return this.optional( element ) || /^d+$/.test( value );
            },
        
            // 字符最小长度
            minlength: function( value, element, param ) {
                var length = $.isArray( value ) ? value.length : this.getLength( value, element );
                return this.optional( element ) || length >= param;
            },
        
            // 字符最大长度
            maxlength: function( value, element, param ) {
                var length = $.isArray( value ) ? value.length : this.getLength( value, element );
                return this.optional( element ) || length <= param;
            },
        
            // 范围长度
            rangelength: function( value, element, param ) {
                var length = $.isArray( value ) ? value.length : this.getLength( value, element );
                return this.optional( element ) || ( length >= param[ 0 ] && length <= param[ 1 ] );
            },
        
            // 最小值
            min: function( value, element, param ) {
                return this.optional( element ) || value >= param;
            },
        
            // 最大值
            max: function( value, element, param ) {
                return this.optional( element ) || value <= param;
            },
        
            // 范围值
            range: function( value, element, param ) {
                return this.optional( element ) || ( value >= param[ 0 ] && value <= param[ 1 ] );
            },
        
            step: function( value, element, param ) {
                var type = $( element ).attr( "type" ),
                    errorMessage = "Step attribute on input type " + type + " is not supported.",
                    supportedTypes = [ "text", "number", "range" ],
                    re = new RegExp( "\b" + type + "\b" ),
                    notSupported = type && !re.test( supportedTypes.join() ),
                    decimalPlaces = function( num ) {
                        var match = ( "" + num ).match( /(?:.(d+))?$/ );
                        if ( !match ) {
                            return 0;
                        }
        
                        // Number of digits right of decimal point.
                        return match[ 1 ] ? match[ 1 ].length : 0;
                    },
                    toInt = function( num ) {
                        return Math.round( num * Math.pow( 10, decimals ) );
                    },
                    valid = true,
                    decimals;
        
                // Works only for text, number and range input types
                // TODO find a way to support input types date, datetime, datetime-local, month, time and week
                if ( notSupported ) {
                    throw new Error( errorMessage );
                }
        
                decimals = decimalPlaces( param );
        
                // Value can't have too many decimals
                if ( decimalPlaces( value ) > decimals || toInt( value ) % toInt( param ) !== 0 ) {
                    valid = false;
                }
        
                return this.optional( element ) || valid;
            },
        
            // 匹配某个元素
            equalTo: function( value, element, param ) {
        
                // Bind to the blur event of the target in order to revalidate whenever the target field is updated
                var target = $( param );
                if ( this.settings.onfocusout && target.not( ".validate-equalTo-blur" ).length ) {
                    target.addClass( "validate-equalTo-blur" ).on( "blur.validate-equalTo", function() {
                        $( element ).valid();
                    } );
                }
                return value === target.val();
            },
        
            // 远程校验
            remote: function( value, element, param, method ) {
                if ( this.optional( element ) ) {
                    return "dependency-mismatch";
                }
        
                method = typeof method === "string" && method || "remote";
        
                var previous = this.previousValue( element, method ),
                    validator, data, optionDataString;
        
                if ( !this.settings.messages[ element.name ] ) {
                    this.settings.messages[ element.name ] = {};
                }
                previous.originalMessage = previous.originalMessage || this.settings.messages[ element.name ][ method ];
                this.settings.messages[ element.name ][ method ] = previous.message;
        
                param = typeof param === "string" && { url: param } || param;
                optionDataString = $.param( $.extend( { data: value }, param.data ) );
                if ( previous.old === optionDataString ) {
                    return previous.valid;
                }
        
                previous.old = optionDataString;
                validator = this;
                this.startRequest( element );
                data = {};
                data[ element.name ] = value;
                $.ajax( $.extend( true, {
                    mode: "abort",
                    port: "validate" + element.name,
                    dataType: "json",
                    data: data,
                    context: validator.currentForm,
                    success: function( response ) {
                        var valid = response === true || response === "true",
                            errors, message, submitted;
        
                        validator.settings.messages[ element.name ][ method ] = previous.originalMessage;
                        if ( valid ) {
                            submitted = validator.formSubmitted;
                            validator.resetInternals();
                            validator.toHide = validator.errorsFor( element );
                            validator.formSubmitted = submitted;
                            validator.successList.push( element );
                            validator.invalid[ element.name ] = false;
                            validator.showErrors();
                        } else {
                            errors = {};
                            message = response || validator.defaultMessage( element, { method: method, parameters: value } );
                            errors[ element.name ] = previous.message = message;
                            validator.invalid[ element.name ] = true;
                            validator.showErrors( errors );
                        }
                        previous.valid = valid;
                        validator.stopRequest( element, valid );
                    }
                }, param ) );
                return "pending";
            }
        }

        
        // 添加类规则，如果时字符串，直接赋值，如果是对象，扩展classRuleSettings
        addClassRules: function( className, rules ) {
            if ( className.constructor === String ) {
                this.classRuleSettings[ className ] = rules;
            } else {
                $.extend( this.classRuleSettings, className );
            }
        },
        
        // 获取某个元素的class规则
        classRules: function( element ) {
            var rules = {},
                classes = $( element ).attr( "class" );
        
            if ( classes ) { 
                $.each( classes.split( " " ), function() {
                    if ( this in $.validator.classRuleSettings ) { 
                        // 防止重复和无用添加
                        $.extend( rules, $.validator.classRuleSettings[ this ] );
                    }
                } );
            }
            return rules;
        },
        
        // 规范化属性规则 由于 html下可以通过属性定义规则
        normalizeAttributeRule: function( rules, type, method, value ) {
        
            // type={ number, range, text} method={min max step}
            if ( /min|max|step/.test( method ) && ( type === null || /number|range|text/.test( type ) ) ) {
                value = Number( value );
        
                // Support Opera Mini, which returns NaN for undefined minlength
                if ( isNaN( value ) ) {
                    value = undefined;
                }
            }
        
            if ( value || value === 0 ) {
                rules[ method ] = value;
            } else if ( type === method && type !== "range" ) {
        
                // Exception: the jquery validate 'range' method
                // does not test for the html5 'range' type
                rules[ method ] = true;
            }
        },
        
        // 获取元素的属性规则
        attributeRules: function( element ) {
            var rules = {},
                $element = $( element ),
                type = element.getAttribute( "type" ),
                method, value;
        
            for ( method in $.validator.methods ) {
        
                // Support for <input required> in both html5 and older browsers
                if ( method === "required" ) {
                    value = element.getAttribute( method );
        
                    // Some browsers return an empty string for the required attribute
                    // and non-HTML5 browsers might have required="" markup
                    if ( value === "" ) {
                        value = true;
                    }
        
                    // Force non-HTML5 browsers to return bool
                    value = !!value;
                } else {
                    value = $element.attr( method );
                }
        
                this.normalizeAttributeRule( rules, type, method, value );
            }
        
            // 'maxlength' may be returned as -1, 2147483647 ( IE ) and 524288 ( safari ) for text inputs
            if ( rules.maxlength && /-1|2147483647|524288/.test( rules.maxlength ) ) {
                delete rules.maxlength;
            }
        
            return rules;
        },
        
        // 数据
        dataRules: function( element ) {
            var rules = {},
                $element = $( element ),
                type = element.getAttribute( "type" ),
                method, value;
        
            for ( method in $.validator.methods ) {
                value = $element.data( "rule" + method.charAt( 0 ).toUpperCase() + method.substring( 1 ).toLowerCase() );
        
                // Cast empty attributes like `data-rule-required` to `true`
                if ( value === "" ) {
                    value = true;
                }
        
                this.normalizeAttributeRule( rules, type, method, value );
            }
            return rules;
        },
        
        // 静态规则
        staticRules: function( element ) {
            var rules = {},
                validator = $.data( element.form, "validator" );
        
            if ( validator.settings.rules ) {
                rules = $.validator.normalizeRule( validator.settings.rules[ element.name ] ) || {};
            }
            return rules;
        },
        
        // 规范化规则及 删除非必需规则
        normalizeRules: function( rules, element ) {
            // Handle dependency check
            $.each( rules, function( prop, val ) {
                // Ignore rule when param is explicitly false, eg. required:false
                if ( val === false ) {
                    delete rules[ prop ];
                    return;
                }
                if ( val.param || val.depends ) {
                    var keepRule = true;
                    switch ( typeof val.depends ) {
                    case "string":
                        keepRule = !!$( val.depends, element.form ).length;
                        break;
                    case "function":
                        keepRule = val.depends.call( element, element );
                        break;
                    }
                    if ( keepRule ) {
                        rules[ prop ] = val.param !== undefined ? val.param : true;
                    } else {
                        $.data( element.form, "validator" ).resetElements( $( element ) );
                        delete rules[ prop ];
                    }
                }
            } );
        
            // Evaluate parameters
            $.each( rules, function( rule, parameter ) {
                rules[ rule ] = $.isFunction( parameter ) && rule !== "normalizer" ? parameter( element ) : parameter;
            } );
        
            // Clean number parameters
            $.each( [ "minlength", "maxlength" ], function() {
                if ( rules[ this ] ) {
                    rules[ this ] = Number( rules[ this ] );
                }
            } );
            $.each( [ "rangelength", "range" ], function() {
                var parts;
                if ( rules[ this ] ) {
                    if ( $.isArray( rules[ this ] ) ) {
                        rules[ this ] = [ Number( rules[ this ][ 0 ] ), Number( rules[ this ][ 1 ] ) ];
                    } else if ( typeof rules[ this ] === "string" ) {
                        parts = rules[ this ].replace( /[[]]/g, "" ).split( /[s,]+/ );
                        rules[ this ] = [ Number( parts[ 0 ] ), Number( parts[ 1 ] ) ];
                    }
                }
            } );
            
            // 
            if ( $.validator.autoCreateRanges ) {
                // Auto-create ranges
                if ( rules.min != null && rules.max != null ) {
                    rules.range = [ rules.min, rules.max ];
                    delete rules.min;
                    delete rules.max;
                }
                if ( rules.minlength != null && rules.maxlength != null ) {
                    rules.rangelength = [ rules.minlength, rules.maxlength ];
                    delete rules.minlength;
                    delete rules.maxlength;
                }
            }
        
            return rules;
        },
        
        // 规范化规则，字符串变对象{}
        normalizeRule: function( data ) {
            if ( typeof data === "string" ) {
                var transformed = {};
                $.each( data.split( /s/ ), function() {
                    transformed[ this ] = true;
                } );
                data = transformed;
            }
            return data;
        },
        
        // 添加自定义的规则
        addMethod: function( name, method, message ) {
            $.validator.methods[ name ] = method;
            $.validator.messages[ name ] = message !== undefined ? message : $.validator.messages[ name ];
            // 默认参个数 < 3时
            if ( method.length < 3 ) {
                $.validator.addClassRules( name, $.validator.normalizeRule( name ) );
            }
        },

 　　2.3  扩展jQuery实例

 

　　a. 结构分析

　　扩展jQuery实例，即可获取通过jQuery实例调用函数

$.extend( $.fn, {
    log: function() {
        console.info("currVal : " + $(this).val());
    }
}); 

6 $('#kw').log("123");

VM415:3 currVal : 输入框里的值

　　b. 具体函数分析

// 操作规则 cmmand : add, remove
        rules: function( command, argument ) {
            var element = this[ 0 ],
                isContentEditable = typeof this.attr( "contenteditable" ) !== "undefined" && this.attr( "contenteditable" ) !== "false",
                settings, staticRules, existingRules, data, param, filtered;
        
            // If nothing is selected, return empty object; can't chain anyway
            if ( element == null ) {
                return;
            }
        
            if ( !element.form && isContentEditable ) {
                element.form = this.closest( "form" )[ 0 ];
                element.name = this.attr( "name" );
            }
        
            if ( element.form == null ) {
                return;
            }
        
            if ( command ) {
                settings = $.data( element.form, "validator" ).settings;
                staticRules = settings.rules;
                existingRules = $.validator.staticRules( element );
                switch ( command ) {
                case "add":
                    $.extend( existingRules, $.validator.normalizeRule( argument ) );
        
                    // Remove messages from rules, but allow them to be set separately
                    delete existingRules.messages;
                    staticRules[ element.name ] = existingRules;
                    if ( argument.messages ) {
                        settings.messages[ element.name ] = $.extend( settings.messages[ element.name ], argument.messages );
                    }
                    break;
                case "remove":
                    if ( !argument ) {
                        delete staticRules[ element.name ];
                        return existingRules;
                    }
                    filtered = {};
                    $.each( argument.split( /s/ ), function( index, method ) {
                        filtered[ method ] = existingRules[ method ];
                        delete existingRules[ method ];
                    } );
                    return filtered;
                }
            }
        
            data = $.validator.normalizeRules(
            $.extend(
                {},
                $.validator.classRules( element ),
                $.validator.attributeRules( element ),
                $.validator.dataRules( element ),
                $.validator.staticRules( element )
            ), element );
        
            // Make sure required is at front
            if ( data.required ) {
                param = data.required;
                delete data.required;
                data = $.extend( { required: param }, data );
            }
        
            // Make sure remote is at back
            if ( data.remote ) {
                param = data.remote;
                delete data.remote;
                data = $.extend( data, { remote: param } );
            }
        
            return data;
        }

// 校验
        valid: function() {
            var valid, validator, errorList;
            
            if ( $( this[ 0 ] ).is( "form" ) ) {
                // 是form元素，直接校验form及其下属元素
                valid = this.validate().form();
            } else {
                // 构建当前元素的validator对象，校验当前元素
                errorList = [];
                valid = true;
                validator = $( this[ 0 ].form ).validate();
                this.each( function() {
                    valid = validator.element( this ) && valid;
                    if ( !valid ) {
                        errorList = errorList.concat( validator.errorList );
                    }
                } );
                validator.errorList = errorList;
            }
            return valid;
        },

// 校验对象
        validate: function( options ) {
        
            // 如果未选中任何元素，打印日志，直接return
            if ( !this.length ) {
                if ( options && options.debug && window.console ) {
                    console.warn( "Nothing selected, can't validate, returning nothing." );
                }
                return;
            }
        
            // 检查当前元素是否已经构建过validator对象
            var validator = $.data( this[ 0 ], "validator" );
            if ( validator ) {
                return validator;
            }
        
            // Add novalidate tag if HTML5.
            this.attr( "novalidate", "novalidate" );
            
            // 创建一个validator对象，new $.validator( options, this[ 0 ] );
            validator = new $.validator( options, this[ 0 ] );
            //  当前元素 data存储 validator
            $.data( this[ 0 ], "validator", validator );
            
            // 如果配置了onsubmit属性
            if ( validator.settings.onsubmit ) {
                // submit绑定点击事件
                this.on( "click.validate", ":submit", function( event ) {
                    // Track the used submit button to properly handle scripted
                    // submits later. 如果当前事件是提交按纽触发
                    validator.submitButton = event.currentTarget;
        
                    // Allow suppressing validation by adding a cancel class to the submit button
                    if ( $( this ).hasClass( "cancel" ) ) {
                        validator.cancelSubmit = true;
                    }
        
                    // Allow suppressing validation by adding the html5 formnovalidate attribute to the submit button
                    if ( $( this ).attr( "formnovalidate" ) !== undefined ) {
                        validator.cancelSubmit = true;
                    }
                } );
        
                // Validate the form on submit
                this.on( "submit.validate", function( event ) {
                    if ( validator.settings.debug ) {
                        // debug 模式下，无需执行submit
                        event.preventDefault();
                    }
                    
                    function handle() {
                        var hidden, result;
        
                        // Insert a hidden input as a replacement for the missing submit button
                        // The hidden input is inserted in two cases:
                        //   - A user defined a `submitHandler`
                        //   - There was a pending request due to `remote` method and `stopRequest()`
                        //     was called to submit the form in case it's valid
                        if ( validator.submitButton && ( validator.settings.submitHandler || validator.formSubmitted ) ) {
                            hidden = $( "<input type='hidden'/>" )
                                .attr( "name", validator.submitButton.name )
                                .val( $( validator.submitButton ).val() )
                                .appendTo( validator.currentForm );
                        }
        
                        if ( validator.settings.submitHandler && !validator.settings.debug ) {
                            result = validator.settings.submitHandler.call( validator, validator.currentForm, event );
                            if ( hidden ) {
        
                                // And clean up afterwards; thanks to no-block-scope, hidden can be referenced
                                hidden.remove();
                            }
                            if ( result !== undefined ) {
                                return result;
                            }
                            return false;
                        }
                        return true;
                    }
        
                    // Prevent submit for invalid forms or custom submit handlers
                    if ( validator.cancelSubmit ) {
                        validator.cancelSubmit = false;
                        return handle();
                    }
                    if ( validator.form() ) {
                        if ( validator.pendingRequest ) {
                            validator.formSubmitted = true;
                            return false;
                        }
                        return handle();
                    } else {
                        validator.focusInvalid();
                        return false;
                    }
                } );
            }
        
            return validator;
        },