时间：2021-07-01 10:21:17 帮助过：1人阅读
实现一个简单的on和off方法
介绍:
Event对象:
funcList: {}, //保存delegate所绑定的方法
ieFuncList :{} //保存ie下的绑定方法
Event 对象中的 on, off 方法,主要调用
Event.addEvent, Event.delegateHandle这两个方法
Event.addEvent: 调用底层的addEventListener添加监听事件
Event.delegateHandle: 当发生事件之后,随着事件的冒泡上升,判断存在事件委托的元素,并执行对应的回调函数
addEvent / offEvent:
obj.addEventListener(type, fn, false);
obj.removeEventListener(type, fn, false);
代码-Event.js
/**
* addEvent
* author laynezhou@tencent.com
*/
window.Event = {};
var Event = {
funcList: {}, //保存delegate所绑定的方法
ieFuncList: {}, //由于保存在ie下绑定的方法
on: function(obj, selector, type, fn) {
if (!obj || !selector) return false;
var fnNew = Event.delegateHandle(obj, selector, fn);
Event.addEvent(obj, type, fnNew);
/* 将绑定的方法存入Event.funcList，以便之后解绑操作 */
if (!Event.funcList[selector]) {
Event.funcList[selector] = {};
}
if (!Event.funcList[selector][type]) {
Event.funcList[selector][type] = {};
}
Event.funcList[selector][type][fn] = fnNew;
},
off: function(obj, selector, type, fn) {
if (!obj || !selector || !Event.funcList[selector]) {
return false;
}
var fnNew = Event.funcList[selector][type][fn];
if (!fnNew) {
return;
}
Event.offEvent(obj, type, fnNew);
Event.funcList[selector][type][fn] = null;
},
delegateHandle: function(obj, selector, fn) {
/* 实现delegate 的转换方法，事件冒泡上升时, 符合条件时才会执行回调函数 */
var func = function(event) {
var event = event || window.event;
var target = event.srcElement || event.target;
var parent = target;
function contain(item, elmName) {
if (elmName.split('#')[1]) { //by id
if (item.id && item.id === elmName.split('#')[1]) {
return true;
}
}
if (elmName.split('.')[1]) { //by class
if (hasClass(item, elmName.split('.')[1])) {
return true;
}
}
if (item.tagName == elmName.toUpperCase()) {
return true; //by tagname
}
return false;
}
while (parent) {
/* 如果触发的元素，属于(selector)元素的子级。 */
if (obj == parent) {
return false; //触发元素是自己
}
if (contain(parent, selector)) {
fn.call(obj, event);
return;
}
parent = parent.parentNode;
}
};
return func;
},
addEvent: function(target, type, fn) {
if (!target) return false;
var add = function(obj) {
if (obj.addEventListener) {
obj.addEventListener(type, fn, false);
} else {
// for ie
if (!Event.ieFuncList[obj]) Event.ieFuncList[obj] = {};
if (!Event.ieFuncList[obj][type]) Event.ieFuncList[obj][type] = {};
Event.ieFuncList[obj][type][fn] = function() {
fn.apply(obj, arguments);
};
obj.attachEvent("on" + type, Event.ieFuncList[obj][type][fn]);
}
}
if (target.length >= 0 && target !== window && !target.tagName) {
for (var i = 0, l = target.length; i < l; i++) {
add(target[i])
}
} else {
add(target);
}
},
offEvent: function(target, type, fn) {
if (!target) return false;
var remove = function(obj) {
if (obj.addEventListener) {
obj.removeEventListener(type, fn, false);
} else {
//for ie
if (!Event.ieFuncList[obj] || !Event.ieFuncList[obj][type] || !Event.ieFuncList[obj][type][fn]) {
return;
}
obj.detachEvent("on" + type, Event.ieFuncList[obj][type][fn], false);
Event.ieFuncList[obj][type][fn] = {};
}
}
if (target.length >= 0 && target !== window && !target.tagName) {
for (var i = 0, l = target.length; i < l; i++) {
remove(target[i])
}
} else {
remove(target);
}
},
};
代码-DEMO.html
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>test</title>
</head>
<body>
<p>测试 Event </p>
<div id=content>
<ul>
<li><button id="btn1">1</button></li>
<li><button id="btn2">2</button></li>
<li><button id="btn3">3</button></li>
<li><button id="btn4">4</button></li>
<li><button id="btn5">5</button></li>
</ul>
<button id="unbind">取消绑定</button>
</div>
<p id="text"></p>
<script src="addEvent.js"></script>
<script>
(function(){
/* 演示demo*/
var $id=function(id)
{
return document.getElementById(id) || id;
}
var outer = $id("content"),
btn = $id("text");
Event.on(outer,'button',"click",add);
Event.on(outer,'#unbind',"click",remove);
//动态添加一个按钮,查看是否有事件响应
var newbtn = document.createElement("button");
var node = document.createTextNode("new button");
newbtn.appendChild(node);
outer.appendChild(newbtn);
function add(){
var e = arguments[0] || window.event;
var target = e.srcElement || e.target;
console.log("target:",target);
btn.innerHTML = target.innerHTML + ' ' + e.type;
}
function remove(){
Event.off(outer,'button',"click",add);
Event.off(outer,'#unbind',"click",remove);
}
})();
</script>
</body>
</html>