JavaScript在不同上下文中的"this" [英] JavaScript 'this' in different context

问题描述

我正尝试如下创建JavaScript对象.

I am trying to create a JavaScript object as follows.

var MyObject = function (parameters) {
    this.parameters = parameters;
    parameters.userFunction(this.MyObjectCallback);
}

MyObject.SOME_STATIC_VARIABLE = 21;

MyObject.prototype = {
    myObjectCallback: function() {
         console.log(this);
    }
}

MyObject对象将接受将传递处理程序的userFunction.用户函数将执行一些逻辑，并将结果传递回实例，例如:

The MyObject object will accept a userFunction to which it will pass a handler. The user function will do some logic and pass the result back to the instance, for example:

new MyObject({userFunction: function(callback) {
   $.post(
        'http://localhost/~knyttl/source.php',
        {},
        callback,
        'json');,
}});

不幸的是，即使正确地调用了callback，但this还是得到了JQuery对象的实例，而不是我想要的MyObject实例.最后，我无法保留MyObject实例.

Unfortunately, even though the callback is properly called, this gets an instance of the JQuery object and not of the MyObject instance as I would like. To conclude, I can not manage to keep the MyObject instance.

我什至不确定这是否是创建JavaScript对象的正确方法.任何建议，我将不胜感激.

I am not even sure, whether this is a correct way of creating JavaScript objects. I will be grateful for any suggestion.

推荐答案

您可以使用.bind绑定特定的this值.我也更正了My的大写字母.

You can bind a specific this value using .bind. Also I corrected the capitalizing of My.

parameters.userFunction(this.myObjectCallback.bind(this));

当调用诸如a.b()之类的函数时，则在b，this === a中.但是，如果您不直接调用它，而仅传递该函数(例如a.b)，然后再调用它，则此绑定会丢失.

When you call a function like a.b(), then inside b, this === a. However, if you do not directly call it but only pass the function (like a.b) and call it later, this binding is lost.

.bind返回一个新函数，该函数现在将jQuery ajax结果接收为this.但是，它将忽略该内容，并使用预定义的(绑定)this调用myObjectCallback.

.bind returns a new function which now receives the jQuery ajax result as this. However, it ignores that and calls myObjectCallback with the predefined (bound) this.

.bind在较旧的浏览器上不可用，但有垫片可用.

.bind is not available on older browsers but there are shims available.

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