var arr = [, , , ];
if (Array.prototype.indexOf) {
alert("你的浏览器支持indexOf方法。");
} else {
alert("你的浏览器不支持indexOf方法。");
}
if (!Array.prototype.indexOf) {
Array.prototype.indexOf = function(item) {
for (var i = ; i < this.length; i++) {
if(this[i]==item){
return i;
}
}
return -;
}
}
alert(arr.indexOf());
alert(arr.indexOf()); 

if (!Array.prototype.indexOf)
{
Array.prototype.indexOf = function(elt /*, from*/)
{
var len = this.length >>> ;
var from = Number(arguments[]) || ;
from = (from < )
? Math.ceil(from)
: Math.floor(from);
if (from < )
from += len;
for (; from < len; from++)
{
if (from in this &&
this[from] === elt)
return from;
}
return -;
};
} 

public class MyList<E> extends ArrayList<E>
{
public void myAdd(E e){
super.add(e);
System.out.println("Add:"+e);
}
} 

var myObject = function(){
}
myObject.prototype.add = function(){
Array.prototype.push.call(this,arguments);
//输出arguments
for(var i=;i<arguments.length;i++){
console.log("Add:"+arguments[i]);
}
}
var obj = new myObject();
obj.add(,,); 

var Obj = function(name){
this.name = name;
}
Obj.prototype.getName = function(){
return this.name;
}
var obj1 =new Obj("zou");
var obj2 = {name:'andy'};
var name = obj1.getName.call(obj2);
alert(name); 

var name = 'goo';
alert(obj1.getName.call(null)); 
（在严格模式下，由于全局对象是null，故会抛出异常：Uncaught TypeError: Cannot read property 'name' of null）

function myobj(){
}
Object.defineProperty(myobj.prototype,'length',{
get:function(){
return this.length_; //这里不能是length。
},
set:function(value){
return this.length_=value;
}
}); 

Object.defineProperty(myobj.prototype,'length',{
get:function(){
return this.length_; //这里不能是length。
}, 
/*set:function(value){
return this.length_=value;
}*/
});
myobj.length = 3; 

Object.defineProperty(myobj.prototype,'length',{
writable:false
});

Object.defineProperty(myobj.prototype,'length',{
configurable:false
});
var obj = new myobj();
delete obj.length; 

Object.defineProperty(myobj.prototype,'length',{
writable:false,
value:'10'
});
var obj = new myobj();
obj.length = 100; 

Object.defineProperty(myobj.prototype,'length',{
value:,
writable:false,
});
var descriptor = Object.getOwnPropertyDescriptor(myobj.prototype, 
"length");
descriptor.writable = true;
Object.defineProperty(myobj.prototype,'length',descriptor); 
Uncaught TypeError: Cannot redefine property: length

Object.defineProperty(myobj.prototype,'length',{
value:,
writable:false,
configurable:true
});
var descriptor = Object.getOwnPropertyDescriptor(myobj.prototype, 
"length");
descriptor.writable = true;
Object.defineProperty(myobj.prototype,'length',descriptor);
myobj.prototype.length = ;
var obj = new myobj();
alert(obj.length); 

var descriptor = Object.getOwnPropertyDescriptor(DOMTokenList.prototype,'length');
descriptor.set = function(value){
this.length = value;
}
Object.defineProperty(DOMTokenList.prototype,'length',descriptor); 

var descriptor = Object.getOwnPropertyDescriptor(DOMTokenList.prototype,'length');
descriptor.set = function(value){
delete DOMTokenList.prototype.length;
this.length = value;
}
Object.defineProperty(DOMTokenList.prototype,'length',descriptor); 

Array.prototype.push.call(document.body.classList,'abc')

DOMTokenList.prototype.push = function(){
Array.prototype.push.call(document.body.classList,Array.prototype.slice.call(arguments));
}