通过引用将JavaScript数组传递给局部变量? [英] Pass JavaScript array to local variable by reference?

问题描述

我在这样的名称空间中有一个JavaScript数组:

I have a JavaScript array inside a namespace like this:

app.collec.box = [];

并且我在同一个名称空间中有一个函数，如下所示:

and I have a function inside the same namespace like this:

app.init = function () {
    var box = this.collec.box;
    // ... code to modify box
};

我认为将局部变量设置为等于对象或对象属性只是对原始变量的引用，但是在更改函数app.collec.box中局部box变量的内容之后，看来我错了不会改变.

I thought that setting a local variable equal to an object or object property was just a REFERENCE to the original, but it seems I am wrong, after changing the contents of the local box variable inside my function, app.collec.box does not change.

请帮助，我在做什么错?我该如何解决?

Please help, what am I doing wrong? how can I solve this?

谢谢.

编辑..这是完整的代码.

var app = {
    collec: {
        box: [],
        cache: []
    },

    init: function () {
        var box = this.collec.box;

        $.ajax({
            url: 'file.json',
            success: function (json) {
                // Map JSON array to box array using Underscore.js _()map
                box = _(json).map(function (o) {
                    return new Model(o);
                });
            }
        });
    }
};

app.init();

推荐答案

引用指向对象，而不是变量. box不是对变量this.collec.box的引用；而是box和this.collec.box是对内存中一个特定对象的引用.您可以通过这两个变量之一来修改此对象的属性，但是不能使用一个变量来修改另一个变量.

References point to objects, not variables. box is not a reference to the variable this.collec.box; rather, box and this.collec.box are references to one specific object in memory. You can modify the properties of this object through either of these variables, but you can't use one variable to modify another variable.

如果要修改this.collec.box所指的内容，则需要像这样直接设置它:

If you want to modify what this.collec.box refers to, you either need to set it directly like this:

this.collec.box = ...;

或使用对this.collec对象的引用并修改其box属性:

or use a reference to the this.collec object and modify its box property:

var x = this.collec;
x.box = ...;

---

编辑:也许有几个图表可以使您更容易理解正在发生的事情.

---

Maybe a couple of diagrams will make it easier to understand what's happening.

分配box = this.collec.box时，实际上是这样:

When you assign box = this.collec.box, this is what actually happens:

this.collec.box -----> (object) <----- box

这两个变量都指向内存中的同一对象，但是box绝没有引用this.collec.box变量.

Both the variables point to the same object in memory, but in no way does box actually refer to the this.collec.box variable.

如果发生这种情况，您期望的结果将起作用:

What you are expecting would work if this happened:

box -----> this.collec.box -----> (object)

但这不会发生.

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