[javascript] How to use a variable for a key in a JavaScript object literal?

Update: As a commenter pointed out, any version of JavaScript that supports arrow functions will also support ({[myKey]:myValue}), so this answer has no actual use-case (and, in fact, it might break in some bizarre corner-cases).

Don't use the below-listed method.


I can't believe this hasn't been posted yet: just use arrow functions with anonymous evaluation!

Completely non-invasive, doesn't mess with the namespace, and it takes just one line:

myNewObj = ((k,v)=>{o={};o[k]=v;return o;})(myKey,myValue);

demo:

_x000D_
_x000D_
var myKey="valueof_myKey";
var myValue="valueof_myValue";
var myNewObj = ((k,v)=>{o={};o[k]=v;return o;})(myKey,myValue);
console.log(myNewObj);
_x000D_
_x000D_
_x000D_

useful in environments that don't support the new {[myKey]: myValue} syntax yet, such as—apparently; I just verified it on my Web Developer Console—Firefox 72.0.1, released 2020-01-08. I stand corrected; just wrap the thing in parenthesis and it works.

(I'm sure you could potentially make some more powerful/extensible solutions or whatever involving clever use of reduce, but at that point you'd probably be better served by just breaking out the Object-creation into its own function instead of compulsively jamming it all inline)


not that it matters since OP asked this ten years ago, but for completeness' sake and to demonstrate how it is exactly the answer to the question as stated, I'll show this in the original context:

var thetop = 'top';
<something>.stop().animate(
    ((k,v)=>{o={};o[k]=v;return o;})(thetop,10), 10
);

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