Is there a one-liner for creating an object literal in Javascript with a key named after a parameter?

Question

i.e.:

assert(createObj('foo', 5)) == {foo: 5}

One implementation would of course be:

function createObj(key, val) {
  var ret = {};
  ret[key] = val;
  return ret;
}

Just wondering if there's a one-liner.

Answer 1

There is, in ES2015:

{
    ['foo']: 123
}

And there is no really simple and "fair" one in ES5.1

References:

• https://github.com/lukehoban/es6features#enhanced-object-literals

Answer 2

It looks like is not possible in pure JavaScript. You need to make the object first, then use [] to set it.

However, is possible in frameworks. For instance, in ES.

Using a variable for a key in a JavaScript object literal

JavaScript set object key by variable