Javascript，并从另一个引用一个名称空间属性

问题描述

假设我有:

var myNamespace = {
      _prop1: 'hello',
      _prop2: _prop1 + ' you!'
};

我现在发现这在加载时在_prop2上会出错.

I'm just now finding out that this will error on _prop2 at load.

我不明白为什么这行不通，我已经在代码中解决了这个问题，但我仍然想了解.

I can't understand why this doesn't work, I've worked around it in my code but I would still like to understand.

推荐答案

尝试设置prop2时，对象尚未初始化，因此prop1和mynamespace的值均未定义.

When you try and set prop2 the object hasn't initialised so the value of prop1 and mynamespace are both undefined.

有两种方法可以实现所需的功能，一种方法是将prop2创建为一个函数，以便它可以动态获取prop1的值

There are a couple of ways to achieve what you want, one way would be to create prop2 as a function so it can dynamically get the value of prop1

var myNamespace = {
      _prop1: 'hello',
      _prop2: function(){ return this._prop1 + ' you!' }
};

另一种方法是在myNamespace初始化之后设置prop2

Another way would be to set prop2 after myNamespace has been initialised

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