参考网上的一个资料，做下备注。
<html>
<head>
<title>js event demo</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0" max-age="0">
</head>
<body>
<h4>js event demo</h4>
</body>
<script type="text/javascript">
//自定义事件
function EventEmitter() {
this.events = {};
}
//绑定事件函数
EventEmitter.prototype.on = function(ename, call){
this.events[ename] = this.events[ename] || [];
this.events[ename].push(call);
}
EventEmitter.prototype.emit = function(ename, _){
var events = this.events[ename];
//取参数，剔除参数ename
var args = Array.prototype.slice.call(arguments, 1);
for(var i = 0; i < events.length; i++){
//调用绑定的事件函数
events[i].apply(null, args);
}
}
function app(){
calltime = 0;
//同一个事件绑定了两个处理函数
this.on('start',function(user, date){
calltime += 1;
console.log('event start: ' + user + " " + date + " " + calltime);
});
this.on('start', function(user, date){
calltime += 1;
console.log('event start: ' + user + " " + date + " " + calltime);
})
}
app.prototype = new EventEmitter();
var a = new app();
//触发事件
a.emit('start', 'fred', new Date());
</script>
</html>