CODEWITHSUNDEEP
javascript
ajwood
ajwood

Reputation: 19027

Dynamic keys in Javascript associative array declaration one-liner

I would expect the following three associative arrays to be identical:

arr1 = { "dynamic":"foo", "bar":"baz" };

key = "dynamic";    
arr2 = { key:"foo", "bar":"baz" };

arr3 = {};
arr3[key] = "foo";
arr3["bar"] = "baz";

In the above examples, arr1 and arr3 are the same, but arr2 is different.

Is it possible to use dynamic keys in the declaration of a javascript associative array?

Upvotes: 19

Views: 19339

Answers (5)

Vladimir Monsanto
Vladimir Monsanto

Reputation: 552

var originalObj = {};//some data here


function addKeyValuePair(originalObj,key,value){
    originalObj = {...originalObj,[key]:value}
};

Upvotes: 0

Brian
Brian

Reputation: 7654

It is now possible to use dynamic keys in the declaration of a javascript object, in any browser/platform that supports ES6 literal shorthands:

key = "dynamic";    
arr2 = {
    [key]: "foo",  // "dynamic": "foo"
    "bar": "baz"
};

Upvotes: 20

Phil M
Phil M

Reputation: 995

Since you asked for a one liner, try this:

var key = 'dynamic', obj = (function(o) { o[key]='foo'; return o;})({bar: 'baz'});

This will make obj equal to {bar: "baz", dynamic: "foo"}

Upvotes: 1

Ramasamy Kasi
Ramasamy Kasi

Reputation: 181

I found a solution for this.

Do as following:

var field='name';

var ourVar={};

ourVar[field] = 'Somethig';

Source: Javascript: variable as array key

Upvotes: 7

ThiefMaster
ThiefMaster

Reputation: 318518

Only the [] syntax works for dynamic keys. You cannot use them in a literal. So your answer is no, it's not possible.

But you can use a literal to create all the static keys and then add the dynamic ones using the [] syntax. That's usually prettier than using the . or [] notation for all elements.

Upvotes: 9

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