javascript 自定义事件

function EventTarget(){
            this.handlers={};
        }
        
        EventTarget.prototype={
            constructor:EventTarget,
            addHandler:function(type,handler){
                if(typeof this.handlers[type]=='undefined'){
                    this.handlers[type]=new Array();
                }
                this.handlers[type].push(handler);
            },
            removeHandler:function(type,handler){
                if(this.handlers[type] instanceof Array){
                    var handlers=this.handlers[type];
                    for(var i=0,len=handlers.length;i<len;i++){
                        if(handler[i]==handler){
                            handlers.splice(i,1);
                            break;
                        }
                    }
                }
            },
            trigger:function(event){
                if(!event.target){
                    event.target=this;
                }
                if(this.handlers[event.type] instanceof Array){
                    var handlers=this.handlers[event.type];
                    for(var i=0,len=handlers.length;i<len;i++){
                        handlers[i](event);
                    }
                }
            }
        }

addHandler方法用于添加事件处理程序，removeHandler方法用于移除事件处理程序，所有的事件处理程序在属性handlers中统一存储管理。调用trigger方法触发一个事件，该方法接收一个至少包含type属性的对象作为参数，触发的时候会查找handlers属性中对应type的事件处理程序。写段代码测试一下。

function onClose(event){
            alert('message:'+event.message);
        }
        
        var target=new EventTarget();
        target.addHandler('close',onClose);
        
        //浏览器不能帮我们创建事件对象了，自己创建一个
        var event={
            type:'close',
            message:'Page Cover closed!'
        };
        
        target.trigger(event);

function extend(subType,superType){
            var prototype=Object(superType.prototype);
            prototype.constructor=subType;
            subType.prototype=prototype;
        }

最后写成的版本就是这样的

<!DOCTYPE html>
<html>
    <head>
        <title>Test</title>
        <style type="text/css" >
            html,body
            {
                height:100%;
                width:100%;
                padding:0;
                margin:0;
            }
        
            .dialog
            {
                position:fixed;
                width:300px;
                height:300px;
                top:50%;
                left:50%;
                margin-top:-200px;
                margin-left:-200px;
                box-shadow:2px 2px 4px #ccc;
                background-color:#f1f1f1;
                z-index:30;
                display:none;
            }
            
            .dialog .title
            {
                font-size:16px;
                font-weight:bold;
                color:#fff;
                padding:4px;
                background-color:#404040;
            }
            
            .dialog .close
            {
                width:20px;
                height:20px;
                margin:3px;
                float:right;
                cursor:pointer;
            }
            
            .pageCover
            {
                width:100%;
                height:100%;
                position:absolute;
                z-index:10;
                background-color:#666;
                opacity:0.5;
                display:none;
            }
        </style>
    </head>
    <body>
    <div id="pageCover" class="pageCover"></div>
    
    <input type="button" value="Dialog Test" onclick="openDialog();"/>
    
    <div id="dlgTest" class="dialog">
        <img class="close" alt="" src="images/close.png">
        <div class="title">Dialog</div>
        <div class="content">
        
        </div>
    </div>
    
    <script type="text/javascript">            
        function EventTarget(){
            this.handlers={};
        }
        
        EventTarget.prototype={
            constructor:EventTarget,
            addHandler:function(type,handler){
                if(typeof this.handlers[type]=='undefined'){
                    this.handlers[type]=new Array();
                }
                this.handlers[type].push(handler);
            },
            removeHandler:function(type,handler){
                if(this.handlers[type] instanceof Array){
                    var handlers=this.handlers[type];
                    for(var i=0,len=handlers.length;i<len;i++){
                        if(handler[i]==handler){
                            handlers.splice(i,1);
                            break;
                        }
                    }
                }
            },
            trigger:function(event){
                if(!event.target){
                    event.target=this;
                }
                if(this.handlers[event.type] instanceof Array){
                    var handlers=this.handlers[event.type];
                    for(var i=0,len=handlers.length;i<len;i++){
                        handlers[i](event);
                    }
                }
            }
        }
        </script>
        
    <script type="text/javascript">
        function extend(subType,superType){
            var prototype=Object(superType.prototype);
            prototype.constructor=subType;
            subType.prototype=prototype;
        }
    </script>
    
    <script type="text/javascript">
        function Dialog(id){
            EventTarget.call(this)
            this.id=id;
            var that=this;
            document.getElementById(id).children[0].onclick=function(){
                that.close();
            }
        }
        
        extend(Dialog,EventTarget);
        
        
        Dialog.prototype.show=function(){
            var dlg=document.getElementById(this.id);
            dlg.style.display='block';
            dlg=null;
        }
        
        Dialog.prototype.close=function(){
            var dlg=document.getElementById(this.id);
            dlg.style.display='none';
            dlg=null;
            this.trigger({type:'close'});
        }
    </script>
    
    <script type="text/javascript">
        function openDialog(){        
            var dlg=new Dialog('dlgTest');
            
            dlg.addHandler('close',function(){
                document.getElementById('pageCover').style.display='none';
            });
            
            document.getElementById('pageCover').style.display='block';
            dlg.show();
        }
    </script>
    </body>
<html>

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原文地址：https://www.cnblogs.com/rongfengliang/p/3606029.html