CODEWITHSUNDEEP
ecmascript-6
mpen
mpen

Reputation: 283023

Is it possible to create a const object with Symbol keys?

e.g.

const AES_256_CBC = Symbol();

const encHeaders = {
   AES_256_CBC: "foo",
}

This of course doesn't work because the key is actually the literal string "AES_256_CBC".

Normally you'd just set your properties after initializing the object to an empty hash,

var encHeaders = {};
encHeaders[AES_256_CBC] = "foo";

But I can't do this and have encHeaders be const, can I?

Upvotes: 1

Views: 51

Answers (2)

mpen
mpen

Reputation: 283023

Figured it out. You can do it with square brackets:

const AES_256_CBC = Symbol();

const encHeaders = Object.freeze({
   [AES_256_CBC]: "foo",
});

console.log(encHeaders[AES_256_CBC]); // foo

The square bracket notation was also added in ES6.

Update: Amended to include Bergi's suggestion

Upvotes: 1

Felix Kling
Felix Kling

Reputation: 816760

But I can't do this and have encHeaders be const, can I?

Yes you can. const has no impact on the value, it only affects the binding itself. That is, you cannot assign a new value to encHeaders but you can certainly mutate the value itself (if it's mutable).

Upvotes: 3

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