Javascript回调丢失'this' [英] Javascript callbacks losing 'this'

问题描述

我有一个发行者，我丢失了这个对象"中的这个".下面一段 javascript 的输出给了我some-id"然后是undefined".当我在回调函数中使用 'this' 时，作用域超出对象并且不能再使用 'this'.如何让回调使用this"或至少可以访问该对象?

I have an issuer where I lose the 'this' inside this 'object'. The output of the following piece of javascript gives me "some-id" and then "undefined". When I use 'this' inside a callback function, the scope goes out of the object and it cannot use 'this' anymore. How can I get the callback to use 'this' or at least have access to the object?

由于我将创建多个对象，因此我将无法创建类似静态"的存储.请帮助这个javascript n00b ;-)

Since I will make multiple objects, I won't be able to create a 'static' like storage. Please help this javascript n00b ;-)

这是我的测试代码，您可以使用它来重现我的问题.我想要的是 CheckBox.doSomething() 返回 this.id 的值，该值应该与此测试的 some-id 匹配案件.

here is my test code that you can use to reproduce my problem. What I would like to have is CheckBox.doSomething() to return the value of this.id which should match some-id for this test case.

function CheckBox(input_id) {
    this.id = input_id;
    this.doSomething();
    $('#some-element').click(this.doSomething);
}

Checkbox.prototype.doSomething = function() {
    alert(this.input_id);
}

var some_box = new CheckBox('some-id');
some_box.doSomething();
$('#some-element').click();

我什至无法让它按照我的意愿工作:

edit: I can't even get this to work as I want it to:

function CheckBox2(input_id) {
    this.id = input_id;
    alert(this.id);
}

CheckBox2.prototype.doSomething = function() {
    alert(this.input_id);
}
var some_box = new CheckBox2('some-id');
some_box.doSomething();

推荐答案

function CheckBox(input_id) {
    this.id = input_id;
    this.doSomething = $.proxy( this.doSomething, this );
    $('#some-element').click(this.doSomething);
}

javascript 等价物"是 Function#bind 但并非在每个浏览器中都可用，而且由于您似乎在使用 jQuery，因此我使用的是 jQuery 等价物 $.proxy

The "javascript equivalent" of this is Function#bind but that is not available in every browser and since it seems you are using jQuery I am using the jQuery equivalent $.proxy

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