Can I use a string as the key in a JavaScript object?

Question

var method,
    obj;

method = function () {
  return "foo";
};

// works
obj = {
  'foo': 'bar'
};

// does not work
obj = {
  method(): 'bar'
};

In ES6 `obj={[method()]:'bar'}`, in ES5 `obj={};obj[method()]='bar'` — elclanrs, Nov 19 '14 at 00:05
I just used bracket notation. It works, but it's ugly and disorganized. Oh well. — rb-, Nov 19 '14 at 01:13
Regarding the duplication: I agree, Bergi, [this](http://stackoverflow.com/a/2274327/2535178) is the most concise answer. I needed to ask the question in more precise terms. — rb-, Nov 23 '14 at 00:11

score 2 · Answer 1 · answered Nov 19 '14 at 00:07

2

You can use square bracket syntax in javascript. This cannot be done when declaring an object literal though. You will have to do something like the following.

obj = {}; 
obj[method()] = "bar";

answered Nov 19 '14 at 00:07

Ian Brindley

2,197
1
19
28

score 1 · Answer 2 · answered Nov 19 '14 at 00:11

1

if you create an empty object first, then call the method as if it was the key, it will assign it how you want it to.

var method = function() {
    return 'bar';
};

var obj = {};

obj[method()] = 'bar';

answered Nov 19 '14 at 00:11

jbg

476
2
9

score 0 · Accepted Answer · answered Nov 19 '14 at 00:09

Not that way.

You CAN do this:

function doStuff() {
  return "foo";
};

var obj = {}
  ;

obj[doStuff()] = 'bar';

And on the subject of methods and subscripting...

This would appear to work, but it's a bad idea and it doesn't work how you might think:

var obj = {}
  ;

obj[doStuff] = 'bar';

What happens is doStuff will coerse as doStuff.toString() and it would sometimes behave as expected.

Can I use a string as the key in a JavaScript object?

3 Answers3