看了网上的一篇文章<< 全面理解javascript的caller,callee,call,apply概念>>,记下代码,备用 <script language="JavaScript">
 /**//*
* 演示arguments的用法,如何获取实参数和形数数
*/
 function argTest(a,b,c,d) {
var numargs = arguments.length; // 获取被传递参数的数值。
var expargs = argTest.length; // 获取期望参数的数值。
alert("实参数目为:"+numargs)
alert("形数数目为:"+expargs)

alert(arguments[0])
alert(argTest[0]) //undefined 没有这种用法
}
//argTest(1,2)
//argTest(1,2,3,4,5)

 /**//*
* arguments不是数组(Array类)
*/

Array.prototype.selfvalue = 1;
 function testAguments() {
alert("arguments.selfvalue="+arguments.selfvalue);
}
//alert("Array.sefvalue="+new Array().selfvalue);
//testAguments();





 /**//*
* 演示函数的caller属性.
* 说明:(当前函数).caller:返回一个对函数的引用,该函数调用了当前函数
*/

 function callerDemo() {
 if (callerDemo.caller) {
var a= callerDemo.caller.arguments[0];
alert(a);
 } else {
alert("this is a top function");
}
}
 function handleCaller() {
callerDemo();
}

//callerDemo();
//handleCaller("参数1","参数2");


 /**//*
* 演示函数的callee属性.
* 说明:arguments.callee:初始值就是正被执行的 Function 对象,用于匿名函数
*/
 function calleeDemo() {
alert(arguments.callee);
}
//calleeDemo();
//(function(arg0,arg1){alert("形数数目为:"+arguments.callee.length)})();


 /**//*
* 演示apply,call函数的用法
* 说明:作用都是将函数绑定到另外一个对象上去运行,两者仅在定义参数方式有所区别:
* apply(thisArg,argArray);
* call(thisArg[,arg1,arg2…] ]);
* 即所有函数内部的this指针都会被赋值为thisArg
*/

 function ObjectA() {
alert("执行ObjectA()");
alert(arguments[0]);
 this.hit=function(msg) {alert(msg)}
this.info="我来自ObjectA"
}
 function ObjectB() {
alert("执行ObjectB()");
//调用ObjectA()方法,同时ObjectA构造函数中的所有this就会被ObjectB中的this替代
ObjectA.apply(this,arguments);//ObjectA.call(this);
alert(this.info);
}
//ObjectB('参数0');


var value="global 变量";
 function Obj() {
this.value="对象!";
}
 function Fun1() {
alert(this.value);
}
//Fun1();
//Fun1.apply(window);
//Fun1.apply(new Obj());
</script>
|
|
| 日 | 一 | 二 | 三 | 四 | 五 | 六 |
---|
26 | 27 | 28 | 29 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
|
公告
常用链接
留言簿(4)
随笔分类
相册
Blog
论坛
积分与排名
最新评论

|
|