• 双向数据绑定的三种方式


    1.手动绑定

    <!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>手动绑定</title>
    </head>
    <body>
    <input q-value="value" type="text" id="input">
    <div q-text="value" id="el"></div>
    <script>
        var elems = [document.getElementById('el'), document.getElementById('input')];
    
        var data = {
            value: 'hello!'
        };
    
        var command = {
            text: function(str){
                this.innerHTML = str;
            },
            value: function(str){
                this.setAttribute('value', str);
            }
        };
    
        var scan = function(){
            /**
             * 扫描带指令的节点属性
             */
            for(var i = 0, len = elems.length; i < len; i++){
                var elem = elems[i];
                elem.command = [];
                for(var j = 0, len1 = elem.attributes.length; j < len1; j++){
                    var attr = elem.attributes[j];
                    if(attr.nodeName.indexOf('q-') >= 0){
                        /**
                         * 调用属性指令,这里可以使用数据改变检测
                         */
                        command[attr.nodeName.slice(2)].call(elem, data[attr.nodeValue]);
                        elem.command.push(attr.nodeName.slice(2));
                    }
                }
            }
        }
    
        /**
         * 设置数据后扫描
         */
        function mvSet(key, value){
            data[key] = value;
            scan();
        }
        /**
         * 数据绑定监听
         */
        elems[1].addEventListener('keyup', function(e){
            mvSet('value', e.target.value);
        }, false);
    
        scan();
    
    </script>
    </body>
    </html>

    2.脏检查机制

    <!DOCTYPE html>
    <html lang="en">
    
    <head>
        <meta charset="UTF-8">
        <title>脏检查机制</title>
    </head>
    
    <body>
    <input q-event="value" ng-bind="value" type="text" id="input">
    <div q-event="text" ng-bind="value" id="el"></div>
    <script>
    
        var elems = [document.getElementById('el'), document.getElementById('input')];
    
        var data = {
            value: 'hello!'
        };
    
        var command = {
            text: function(str) {
                this.innerHTML = str;
            },
            value: function(str) {
                this.setAttribute('value', str);
            }
        };
    
        var scan = function(elems) {
            for (var i = 0, len = elems.length; i < len; i++) {
                var elem = elems[i];
                elem.command = {};
                for (var j = 0, len1 = elem.attributes.length; j < len1; j++) {
                    var attr = elem.attributes[j];
                    if (attr.nodeName.indexOf('q-event') >= 0) {
                        /**
                         * 调用属性指令
                         */
                        var dataKey = elem.getAttribute('ng-bind') || undefined;
                        /**
                         * 进行数据初始化
                         */
                        command[attr.nodeValue].call(elem, data[dataKey]);
                        elem.command[attr.nodeValue] = data[dataKey];
                    }
                }
            }
        };
    
        var digest = function(elems) {
            /**
             * 扫描带指令的节点属性
             */
            for (var i = 0, len = elems.length; i < len; i++) {
                var elem = elems[i];
                for (var j = 0, len1 = elem.attributes.length; j < len1; j++) {
                    var attr = elem.attributes[j];
                    if (attr.nodeName.indexOf('q-event') >= 0) {
                        /**
                         * 调用属性指令
                         */
                        var dataKey = elem.getAttribute('ng-bind') || undefined;
    
                        /**
                         * 进行脏数据检测,如果数据改变,则重新执行指令,否则跳过
                         */
                        if(elem.command[attr.nodeValue] !== data[dataKey]){
    
                            command[attr.nodeValue].call(elem, data[dataKey]);
                            elem.command[attr.nodeValue] = data[dataKey];
                        }
                    }
                }
            }
        }
    
        /**
         * 初始化数据
         */
        scan(elems);
    
        function $digest(value){
            var list = document.querySelectorAll('[ng-bind='+ value + ']');
            digest(list);
        }
    
        elems[1].addEventListener('keyup', function(e) {
            data.value = e.target.value;
            $digest(e.target.getAttribute('ng-bind'));
        }, false);
    
    </script>
    </body>
    </html>

    3.数据劫持

    <!DOCTYPE html>
    <html lang="en">
    
    <head>
        <meta charset="UTF-8">
        <title>前端数据劫持</title>
    </head>
    
    <body>
    <input q-value="value" type="text" id="input">
    <div q-text="value" id="el"></div>
    <script>
        var elems = [document.getElementById('el'), document.getElementById('input')];
    
        var data = {
            value: 'hello!'
        };
    
        var command = {
            text: function(str) {
                this.innerHTML = str;
            },
            value: function(str) {
                this.setAttribute('value', str);
            }
        };
    
        var scan = function() {
            /**
             * 扫描带指令的节点属性
             */
            for (var i = 0, len = elems.length; i < len; i++) {
                var elem = elems[i];
                elem.command = [];
                for (var j = 0, len1 = elem.attributes.length; j < len1; j++) {
                    var attr = elem.attributes[j];
                    if (attr.nodeName.indexOf('q-') >= 0) {
                        /**
                         * 调用属性指令
                         */
                        command[attr.nodeName.slice(2)].call(elem, data[attr.nodeValue]);
                        elem.command.push(attr.nodeName.slice(2));
    
                    }
                }
            }
        }
    
        var bValue;
        /**
         * 定义属性设置劫持
         */
        var defineGetAndSet = function(obj, propName) {
            try {
                Object.defineProperty(obj, propName, {
                    get: function() {
                        return bValue;
                    },
                    set: function(newValue) {
                        bValue = newValue;
                        scan();
                    },
    
                    enumerable: true,
                    configurable: true
                });
            } catch (error) {
                console.log("browser not supported.");
            }
        }
        /**
         * 初始化数据
         */
        scan();
    
        /**
         * 可以理解为做数据劫持监听
         */
        defineGetAndSet(data, 'value');
    
        /**
         * 数据绑定监听
         */
        if(document.addEventListener){
            elems[1].addEventListener('keyup', function(e) {
                data.value = e.target.value;
            }, false);
        }else{
            elems[1].attachEvent('onkeyup', function(e) {
                data.value = e.target.value;
            }, false);
        }
    
    </script>
    </body>
    
    </html>

  • 相关阅读:
    [Leetcode Week3]Evaluate Division
    [Leetcode Week3]Course Schedule
    [Leetcode Week3]Clone Graph
    [Leetcode Week2]Sort List
    [Leetcode Week2]Sort Colors
    [Leetcode Week2]Merge Intervals
    [Leetcode Week1]Longest Substring Without Repeating Characters
    哈夫曼树的数组实现
    cocos2d-x3.16 default模式项目 Android Studio C++文件编译失败问题
    html display和visibility在资源加载上的区别
  • 原文地址:https://www.cnblogs.com/xutongbao/p/9924952.html
Copyright © 2020-2023  润新知