字符串作为javascript数组的键-Stringsaskeysofarrayinjavascript

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

在Javascript中有两种类型的数组:标准数组和关联数组

• [ ] - standard array - 0 based integer indexes only
• []-标准数组- 0基于整数索引。
• { } - associative array - Javascript objects where keys can be any strings
• {}关联数组- Javascript对象，其中键可以是任何字符串。

So when you define:

所以当你定义:

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

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.

您正在定义一个标准数组，其中索引只能是整数。当你做arr(“某物”)的时候(你使用的是索引)不是一个整数，你基本上是在给arr对象定义一个属性(所有东西都是Javascript的对象)。但您并没有向标准数组添加元素。

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for( var i = arr.length; i--; console.log( arr[ i ] ) );

for(var i = arr.length);我,;控制台。测井(arr[i]);

This will only give you the numeric indices, of course, but you can still loop over both numeric indices and string keys of your array like this:

当然，这只会给你数字索引，但是你仍然可以对数组的数字索引和字符串键进行循环:

for (var x in arr) {
    console.log(x + ": " + arr[x]);
}
/* (console output):
     0: 0
     1: 1
     2: 2
     3: 3
     something: aught
*/