Javascript闭包和'这个'

Question

我有一个问题，我创建的对象看起来像这样：

var myObject = {

    AddChildRowEvents: function(row, p2) {

        if(document.attachEvent) {

            row.attachEvent('onclick', function(){this.DoSomething();});

        } else {

            row.addEventListener('click', function(){this.DoSomething();}, false);

        }

    },

    DoSomething: function() {

        this.SomethingElse(); //<-- Error here, object 'this' does not support this method.

    }

}

问题是当我进入'DoSomething'函数时，'this'不会引用'myObject'我做错了什么？

Answer 1

当函数被调用时，“this”指的是行。如果你想拥有这个对象，你可以这样做：]AddChildRowEvents: function(row, p2) {&nbsp; &nbsp; var theObj = this;&nbsp; &nbsp; if(document.attachEvent) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;row.attachEvent('onclick', function(){theObj.DoSomething();});&nbsp; &nbsp; } else {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;row.addEventListener('click', function(){theObj.DoSomething();}, false);&nbsp; &nbsp; }},调用该函数时，它可以访问定义函数时在范围内的变量theobj。

Answer 2

this总是指内部函数，如果你有嵌套函数，你必须创建另一个变量并指向它this。var myObject = {&nbsp; &nbsp; AddChildRowEvents: function(row, p2) {&nbsp; &nbsp; &nbsp; &nbsp; var that = this;&nbsp; &nbsp; &nbsp; &nbsp; if(document.attachEvent) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; row.attachEvent('onclick', function(){that.DoSomething();});&nbsp; &nbsp; &nbsp; &nbsp; } else {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; row.addEventListener('click', function(){that.DoSomething();}, false);&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; }}

Answer 3

这是闭包的常见问题。要解决它尝试这样的事情：var myObject = {&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; AddChildRowEvents: function(row, p2) {&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; var self = this;&nbsp; &nbsp; &nbsp; &nbsp; if(document.attachEvent) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;row.attachEvent('onclick', function(){this.DoSomething(self);});&nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; } else {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;row.addEventListener('click', function(){this.DoSomething(self);}, false);&nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; },&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; DoSomething: function(self) {&nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; self.SomethingElse();&nbsp;&nbsp; &nbsp; }}