字符串作为JavaScript数组的钥匙 [英] Strings as keys of array in javascript

问题描述

为什么要使用字符串作为数组键，控制台显示该数组没有这些声明的值，并在此值，其中键是遍历字符串不显示？虽然我可以让他们的价值。

Why using strings as keys of array, console is showing that array without these declared values and while iterating by this values where keys are string aren't displayed? , although i can get value of them.

>> var arr = [ 0, 1, 2, 3 ];
   undefined

>> arr["something"] = "aught";
   "aught"

>> arr
   [0, 1, 2, 3]

>> arr["something"]
   "aught"

>> for( var i = arr.length; i--; console.log( arr[ i ] ) );
   3
   2
   1
   0

据我所知，数组是已经实施了某种枚举界面中的JavaScript引擎对象。
最有意思的是，国米preTER 是不扔警告或错误，所以我花了几天的搜索，其中数据可能丢失的时间。
我现在，我错了，我用 [] 而不是 {}

I understand that arrays are objects which has implemented some kind of 'enumerate' interface in javascript's engine. Most interesting is that interpreter isn't throwing either warning or error so i spent a few of time of searching for where the data could be lost. I now, I was wrong and I used [] instead of {}

推荐答案

在JavaScript的有2个类型数组：标准数组和关联数组

In javascript there are 2 type of arrays: standard arrays and associative arrays

• [] - 标准阵列 - 只有0基于整数索引


• {} - 关联数组 - JavaScript对象，其中的键可以是任意的字符串

• [ ] - standard array - 0 based integer indexes only
• { } - associative array - javascript objects where keys can be any strings

所以，当你定义：

var arr = [ 0, 1, 2, 3 ];

要定义一个标准的数组，其中指标只能是整数。当你做改编[东西] ，因为的东西（这是你作为指数使用的）是不是整数你基本上是定义一个属性添加到改编对象（一切都在JavaScript对象）。但你是不是添加元素的标准阵列。

you are defining a standard array where indexes can only be integers. When you do arr["something"] since something (which is what you use as index) is not an integer you are basically defining a property to the arr object (everything is object in javascript). But you are not adding an element to the standard array.

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