Share an encapsulated javascript event queue function code to solve the problem of binding events-JS Tutorial-php.cn

Share an encapsulated javascript event queue function code to solve the problem of binding events

伊谢尔伦

Release： 2017-07-22 11:01:03

Original

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There are several minor problems when using addEventListener() or attachEvent() to bind events in JavaScript:

1. Anonymous functions added using addEventListener() or attachEvent() Cannot be removed.

var oBtn = document.getElementById(&#39;btn&#39;);
oBtn.addEventListener(&#39;click&#39;,function(){
    alert(&#39;button is clicked&#39;)
},false)
oBtn.reomveEventListener(&#39;click&#39;,function(){
    alert(&#39;button is clicked&#39;)
},false)
//oBtn上的事件无法移除，因为传入的是一个匿名函数

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2. In ie6-ie8, the reverse order execution problem of using attachEvent() to bind multiple events.

var oBtn = document.getElementById(&#39;btn&#39;);
oBtn.attachEvent(&#39;onclick&#39;,function(){
    alert(1)
})
oBtn.attachEvent(&#39;onclick&#39;,function(){
    alert(2)
})
oBtn.attachEvent(&#39;onclick&#39;,function(){
    alert(3)
})
//ie9+   下执行顺序1、2、3
//ie6-ie8下执行顺序3、2、1

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Solve the problem

I want to write a cross-browser event binding module so that it can be reused in the future. At the same time, I want to solve the appeal problem. JQuery internally uses event queues and data caching mechanisms to solve this problem. I looked at the relevant source code and found that it is really complicated. I tried some methods myself and managed to achieve it. The code snippet posted was originally written in an object-oriented way. I didn't want it to be complicated, so I changed it to functions.

/*绑定事件的接口
 *
 *@param    {dom-DOM}和{type-string}和{fn-function}  可选参数{fnName-string}
 *@execute  创建事件队列，添加到DOM对象属性上，
            将事件处理程序(函数)加入事件队列
            可为事件处理程序添加一个标识符，用于删除指定事件处理程序
  */
 function bind(dom,type,fn,fnName){
    dom.eventQueue = dom.eventQueue || {};
    dom.eventQueue[type] = dom.eventQueue[type] || {};
    dom.handler = dom.handler || {};
    if (!fnName) {
        var index = queueLength(dom,type);
        dom.eventQueue[type][&#39;fnQueue&#39;+index] = fn;
    }
    else {
        dom.eventQueue[type][fnName] = fn;
    };
    if (!dom.handler[type]) bindEvent(dom,type);
};
/*绑定事件
 *
 *@param    {dom-DOM}和{type-string}
 *@execute  只绑定一次事件，handler用于遍历执行事件队列中的事件处理程序(函数)
 *@caller   bind()
 */
function bindEvent(dom,type){
    dom.handler[type] = function(){
        for(var guid in dom.eventQueue[type]){
            dom.eventQueue[type][guid].call(dom);
        }
    };
    if (window.addEventListener) {
        dom.addEventListener(type,dom.handler[type],false);
    }
    else {
        dom.attachEvent(&#39;on&#39;+type,dom.handler[type]);
    };
};
/*移除事件的接口
 *
 *@param    {dom-DOM}和{type-string} 可选参数{fnName-function}
 *@execute  如果没有标识符，则执行unBindEvent()
            如果有标识符，则删除指定事件处理程序，如果事件队列长度为0,执行unBindEvent()
  */
function unBind(dom,type,fnName){
    var hasQueue = dom.eventQueue && dom.eventQueue[type];
    if (!hasQueue) return;
    if (!fnName) {
        unBindEvent(dom,type)
    }
    else {
        delete dom.eventQueue[type][fnName];
        if (queueLength(dom,type) == 0) unBindEvent(dom,type);
    };
};
/*移除事件
 *
 *@param    {dom-DOM}和{type-string}
 *@execute  移除绑定的事件处理程序handler，并清空事件队列
 *@caller   unBind()
 */
function unBindEvent(dom,type){
    if (window.removeEventListener) {
        dom.removeEventListener(type,dom.handler[type])
    }
    else {
        dom.detachEvent(type,dom.handler[type])
    }
    delete dom.eventQueue[type];
};
/*判断事件队列长度
 *
 *@param    {dom-DOM}和{type-string}
 *@caller   bind() unBind()
 */
function queueLength(dom,type){
    var index = 0;
    for (var length in dom.eventQueue[type]){
        index++ ;
    }
    return index;
};

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How to use

var oBtn = document.getElementById(&#39;btn&#39;);
//绑定事件
//为button同时绑定三个click事件函数
//ie6-ie8下执行顺序不变
bind(oBtn,&#39;click&#39;,function(){
    alert(1);
})
bind(oBtn,&#39;click&#39;,function(){
    alert(2);
},&#39;myFn&#39;)
bind(oBtn,&#39;click&#39;,function(){
    alert(3);
})
//移除事件
//移除所有绑定的click事件函数，支持移除匿名函数
unBind(oBtn,&#39;click&#39;)
//只移除标识符为myfn的事件函数
unBind(oBtn,&#39;click&#39;,&#39;myFn&#39;)

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