Javascript中对象文字的动态键 [英] dynamic keys for object literals in Javascript

问题描述

好的，所以我正在研究Nodes中的一个项目，我遇到了一个关于对象文字中的键的小问题，我有以下设置：

Ok so I'm working away on a project in Nodes, and I've come across a small problem with the keys in object literals, I have the following set-up:

var required = {
    directories : {
        this.applicationPath                    : "Application " + this.application + " does not exists",
        this.applicationPath + "/configs"       : "Application config folder does not exists",
        this.applicationPath + "/controllers"   : "Application controllers folder does not exists",
        this.applicationPath + "/public"        : "Application public folder does not exists",
        this.applicationPath + "/views"         : "Application views folder does not exists"
    },
    files : {
        this.applicationPath + "/init.js"               : "Application init.js file does not exists",
        this.applicationPath + "/controllers/index.js"  : "Application index.js controller file does not exists",
        this.applicationPath + "/configs/application.js": "Application configs/application.js file does not exists",
        this.applicationPath + "/configs/server.js"     : "Application configs/server.js file does not exists"
    }
}

好的你们很多人会看看这个，并认为它看起来没问题，但编译器一直告诉我，我错过了一个：（冒号），我不是，它好像是 + 或者。都会影响编译器。

Ok so many of you will look at this and think it look's OK, but the compiler keeps telling me that I am missing a : (colon), which im not, it seems like the + or and the . are both effecting the compiler.

现在我相信（不确定），对象文字在编译时创建，而不是在运行时创建，这意味着动态变量，如 this.applicationPath 和连接不会是可用:( :(

Now i believe (not sure), that object literals are created at compile time, and not run-time, meaning that dynamic variables such as this.applicationPath and concatenation are not going to be available :( :(

在不必重写大块代码的情况下，克服这类障碍的最佳方法是什么。

What's the best way to overcome an obstacle like this without having to rewrite large chunks of code.

推荐答案

设置动态密钥的唯一方法是使用括号nota ：

The only way you can set dynamic keys is with bracket notation:

required.directories[this.applicationPath + "/configs"] = "Application config folder does not exists";

（当然无论你做什么定义， this.applicationPath 必须存在）

(of course wherever you do this definition, this.applicationPath must exist)

但你在键中需要 this.applicationPath 吗？你如何访问这些价值观？也许您可以从用于访问属性的任何值中删除 this.applicationPath 。

But do you need this.applicationPath in the keys? How do you access theses values? Maybe you can just remove this.applicationPath from whatever value you use to access the properties.

但是如果你需要它：

如果你想避免重复大量的代码，你可以使用数组来初始化密钥： / p>

You could use an array to initialize the keys if you want to avoid repeating a lot of code:

var dirs = ['configs', 'controllers', ...];
var files = ['init.js', 'controllers/index.js', ...];

var required = { directories: {}, files: {} };
required.directories[this.applicationPath] = "Application " + this.application + " does not exists";

for(var i = dirs.length; i--;) {
    required.directories[this.applicationPath + '/' + dirs[i]] = "Application " + dirs[i] + " folder does not exists";
}

for(var i = files.length; i--;) {
    // same here
}

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