<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<style>
#div1{width:100px;height:100px;background:red}
</style>
<script>
function $(varta){
if(typeof varta == 'function'){ // 当前传值类型是函数，直接用window.onload加载
window.onload = varta;
}else if(typeof varta =='string'){ //当前传值类型是字符串 返回document.getELmentById() 进行操作
return document.getElementById(varta)
}else if(typeof varta == 'object'){ //当前传值为对象 直接返回本身
return varta;
}
}
$(function(){
$('div1').onclick=function(){
$(this).style.background = 'green'
}
})
</script>
</head>
<body>
<div id="div1"></div>
</body>
</html>
只要是应用typeof 来判断传值