Notes on arguments in js
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<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta http-equiv="X-UA-Compatible" content="IE=EmulateIE7" />
<title>water_down_前端开发 </title>
<style type="text/css">
body{margin:0;padding:0}
</style>
</head>
<body>
water Dwon!
</body>
<script type="text/javascript">
var waterDown = function(funa, funb){
/*
* arguments 对象只有函数开始才会创建
* 先看一下arguments的类型 ie和opera下均为[object Object]，
* 但是ff、chrome、safari下直接为[object Arguments], 说明这个arguments有特殊性
*/
alert(Object.prototype.toString.apply(arguments));
/*
* 看一下它的实例 function Object() { [native code] }
* 是一个Object类型的实例
* arguments = {
* 0 : "water",
* 1 : "down",
* 2 : "w",
* 3 : "d"
* }
* 当然这样的0，1，2...n 这样的属性是不能用 arguments.n 来调用的
* 但是可以用访问数组元素的方式来用，arguments[n]
* 然后又添加了一些属性和方法，感觉似数组吧
* length属性 参数的个数
*/
alert(arguments.constructor)
//alert(["a","b"].constructor)
/*
* callee 返回正被执行的 Function 对象
* 递归就不用说了，都知道
*/
console.log(arguments.length) //控制台上输出实际传入的参数个数
console.log(arguments.callee.length) //形参的个数 就是funa，funb
/*
* caller 返回一个对函数的引用，就是调用当前函数的函数。
* 如果函数是由顶层调用的，那么 caller包含的就是 null
*/
if(arguments.callee.caller){
//alert(waterDown.caller.toString())
alert(arguments.callee.caller.toString())
}else{
alert("No wrap Function!")
}
/*
* 把arguments 转换成真正的数组
*/
var A = Array.prototype.slice.call(arguments);
alert(Object.prototype.toString.apply(A));
}
waterDown("water", "down", "w", "d");
!function(){
/*
* 调用waterDown函数 此时waterDown.caller就是当前匿名函数
* 而waterDown.caller.toString() 就等于把当前匿名函数反编译喽
*/
waterDown("waterDown");
}()
</script>
</html>
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