如何使用Javascript文字表示法创建关联数组

I understand that there are no associative arrays in javascript, only objects.

我知道javascript中没有关联数组，只有对象。

However I can create an array with string keys using bracket notation like this:

但是，我可以使用括号表示法创建一个包含字符串键的数组，如下所示：

var myArray = [];
myArray['a'] = 200; 
myArray['b'] = 300; 
console.log(myArray); //prints [a: 200, b: 300]

so, I want to do the exact same thing without using bracket notation

所以，我想在不使用括号表示的情况下做同样的事情

var myNewArray = [a: 200, b: 300]; //getting error - Unexpected token:

this does not work either

这也不起作用

var myNewArray = ['a': 200, 'b': 300]; //same error, why can I not create?

5 个解决方案

#1

Javascript has no associative arrays, just objects. Even JS arrays are basically just objects, just with the special thing that the property names are numbers (0,1,...).

Javascript没有关联数组，只有对象。甚至JS数组基本上也只是对象，只是特殊的东西，属性名称是数字（0,1，...）。

So look at your code first:

所以先看看你的代码：

var myArray = []; // creating a new array object
myArray['a'] = 200; // setting the attribute a to 200
myArray['b'] = 300;  // setting the attribute b 300

Its important to understand that myArray['a'] = 200; is identical to myArray.a = 200;!

重要的是要理解myArray ['a'] = 200;与myArray.a = 200相同;！

So to start with what you want: You can't create a javascript array and pass no number attributes to it in one statement.

所以从你想要的开始：你不能创建一个javascript数组，并在一个语句中不传递任何数字属性。

But this is probably not what you need! Probably you just need a JS object, what is basically the same as an associative array, dictionary, or map in other languages: It maps strings to values. And that can be done easily:

但这可能不是你所需要的！可能你只需要一个JS对象，它与其他语言中的关联数组，字典或映射基本相同：它将字符串映射到值。这很容易做到：

var myObj = {a: 200, b: 300};

But it's important to understand that this differs slightly from what you did. myObj instance of Array will return false, because myObj is not an ancestor from Array in the prototype chain.

但重要的是要明白，这与你所做的略有不同。 myObj Array的实例将返回false，因为myObj不是原型链中Array的祖先。

#2

You can using Map:

你可以使用Map：

var arr = new Map([ 
   ['key1', 'User'], 
   ['key2', 'Guest'], 
   ['key3', 'Admin'], 
]);
var res = arr.get('key2');  
console.log(res); // The value is 'Guest'

#3

You want to use an object in this case

在这种情况下，您想要使用对象

var myObject = {'a' : 200, 'b' : 300 };

This answer links to a more in-depth explanation: How to do associative array/hashing in JavaScript (http://blog.xkoder.com/2008/07/10/javascript-associative-arrays-demystified/)

这个答案链接到一个更深入的解释：如何在JavaScript中进行关联数组/散列（http://blog.xkoder.com/2008/07/10/javascript-associative-arrays-demystified/）

#4

Arrays and Objects are different things.

数组和对象是不同的东西。

For an object, you can do things like:

对于对象，您可以执行以下操作：

var obj = { "property1": "value1" };
obj.property2 = "value2";

For arrays, you have to do this:

对于数组，您必须这样做：

var arr = [];
arr[0] = "value";

#5

Well, you are creating an array, which is in fact an object.

好吧，你正在创建一个数组，实际上是一个对象。

var arr = [];
arr.map;
// function(..)
arr['map'];
// function(..)

arr['a'] = 5;

console.log(arr instanceof Object); // true

You can add fields and functions to arr. It does not "insert" them to the array though (like arr.push(...))

您可以向arr添加字段和函数。它不会将它们“插入”到数组中（如arr.push（...））

You can refer to an object fields with [] syntax

您可以使用[]语法引用对象字段

#1