CODEWITHSUNDEEP
javascriptarraysassociative-array
John Boe
John Boe

Reputation: 3611

Creating some associative array in JavaScript

I have an object which contains an array, and I want it to contain an associative array so keys are strings. How can I do it?

This does not work:

{profiles: { easy:["example" : 1], advanced:["example" : 1] }

I wanted to avoid

console.log({profiles: { easy: {"example": 1}, advanced:{"example": 1} })

Because that easy and advanced members are not displayed as an array but as an object.

Another way I know is this:

array['key2'] = 'new value';

but that is not part of the object, so I would need to split the command for multiple lines - which is not what I want.

PHP has something like array("mykey" => "myValue"), but does JavaScript have something similar?

Yet I don't want to use frameworks. This is JavaScript only.

Upvotes: 3

Views: 26263

Answers (2)

webdeb
webdeb

Reputation: 13211

wanted to avoid console.log({profiles: { easy:{"example" : 1},advanced:{"example" : 1} })

Why? Is there a reason to avoid language-specific features?

If I told you you can do this (should be avoided):

var array = [];
array["foo"] = "bar";
array.foo // -> bar

The problems with it:

array.length // -> 0

So, even if you can apply properties to mostly everything in JavaScript like:

var str = "hello";
str.type = "greetings";

you shouldn't screw the language...

This is the normal way of creating key:value maps, objects:

var obj = {foo: "bar"}
obj.foo // -> bar

Why not do it just like the language is designed to?

Upvotes: 3

Quentin
Quentin

Reputation: 943207

JavaScript doesn't have "associative arrays".

It has objects, which you can store values on in named properties.

It has arrays, which store an ordered set of values via integer properties. Since they are a type of object, you can also store named values on them (but you can't create them using the literal syntax, only add them after the array is created) but this isn't considered good practise and they will be ignored by just about anything that has special case handling for arrays.

As of ES6 it also has Maps which are similar to objects in that you can give them named values, but also to arrays in that order is preserved. There is no literal syntax for creating a Map.

Upvotes: 11

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