Javascript：在自己的键的函数中的对象文字引用而不是'this' [英] Javascript: Object Literal reference in own key's function instead of 'this'

问题描述

在一个函数中引用一个对象文字是否有问题，该函数是该文字的一部分？它似乎工作得很好，但我想确保没有其他含义。

Is it problematic to reference an object literal within a function which is part of that very literal? It seems to work just fine, but I want to make sure there aren't other implications.

以下是我所说的一个例子：

Here's an example of what I'm talking about:

而不是：

var obj = {
    key1: "it",
    key2: function(){return this.key1 + " works!"}
};
alert(obj.key2());

使用：

var obj = {
    key1: "it",
    key2: function(){return obj.key1 + " works!"}
};
alert(obj.key2());

推荐答案

两者都有问题。

var obj = {
    key1: "it",
    key2: function(){ return this.key1 + " works!" }
};
var func = obj.key2;
alert(func()); // error

未调用 func 时作为 obj 的方法， 此 可以引用其他内容（在此处：全局对象 window ）。

When func is not called as a method of obj, this can reference something else (in here: the global object "window").

var obj = {
    key1: "it",
    key2: function(){ return obj.key1 + " works!" }
};
var newref = obj;
obj = { key1: "something else"; };
alert(newref.key2()); // "something else works"

在这里我们从另一个引用访问该对象，尽管<$函数中的c $ c> obj 现在可能指向其他一些对象。

In here we access the object from another reference, though the obj in the function may now point to some other object.

所以你必须选择哪种情况更有可能。如果你真的想让它变得安全，你可以使用一个封闭，其中 obj 的作用域是无法改变的：

So you will have to choose which case is more likely. If you really want to make it safe, you can use a closure where obj is scoped and can't be changed:

var obj = (function(){
    var local = {
        key1: "it",
        key2: function(){ return local.key1 + " works always!" }
    };
    return local;
})();

或者 bind（） 对象的函数：

or you bind() the function to the object:

var obj = {
    key1: "it",
    key2: function(){ return this.key1 + " works always!" }
}
obj.key2 = obj.key2.bind(obj);

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