js中this的用法

I am creating a Javascript object that contains a function that executes a jQuery each method like the following:

function MyClass {

  Method1 = function(obj) { 
    // Does something here
  }

  Method2 = function() {
    $(".SomeClass").each(function() {

       // 1          2
       this.Method1(this);

    });
  }

}

I guess you could do something like this:

function MyClass {
     Method1 = function(obj) {
         //do something here
     }

     Method2 = function () {
          var containingClass = this;
          $(".SomeClass").each(function () {
             containingClass.Method1(this);
           });
        }
    }
}

This means that every time the passed-in function is executed (which is once for every element matched) the 'this' keyword points to the specific DOM element. Note that 'this' does not point to a jQuery object.
 
Personally, I prefer using explicit parameters. This way, it is more easily readable:

$('#rotfl').each(function(index, domObject)
{
   var jQueryObject = $(domObject);
   // code
});

 

 To answer your question: JavaScript has dynamic static scope. You can do the following:

var that = this;
$('#rotfl').each(function(index, domObject)
{
   var jQueryObject = $(domObject);
   that.DoSomething();
   // code
});

this是js的一个关键字，随着函数使用场合不同，this的值会发生变化。但是总有一个原则，那就是this指的是调用函数的那个对象。

1、纯粹函数调用。

function test() {    this.x = 1;    alert(x);}test();

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其实这里的this就是全局变量。看下面的例子就能很好的理解其实this就是全局对象Global。

var x = 1;function test() {    alert(this.x);}test();//1var x = 1;function test() {    this.x = 0;}test();alert(x);//0

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2、作为方法调用，那么this就是指这个上级对象。

function test() {    alert(this.x);}var o = {};o.x = 1;o.m = test;o.m(); //1

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3、作为构造函数调用。所谓构造函数，就是生成一个新的对象。这时，这个this就是指这个对象。

function test() {    this.x = 1;}var o = new test();alert(o.x);//1

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4、apply调用

this指向的是apply中的第一个参数。

var x = 0;function test() {    alert(this.x);}var o = {};o.x = 1;o.m = test;o.m.apply(); //0o.m.apply(o);//1

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当apply没有参数时，表示为全局对象。所以值为0。