Creating a javascript object with an optional key

Asked Jan 15 '17 at 07:29

Active Jan 15 '17 at 07:34

Viewed 1,404 times

I'm looking for an idiomatic method of creating an object with an optional key, i.e. the shortest way of doing the following:

let obj = {a: 1}
if(condition)
    obj['b'] = 2
console.log(obj)

One way I've thought of is:

console.log({a: 1, ...(condition ? {b: 2} : {})})

But is there a better way?

edited Jan 15 '17 at 07:34

asked Jan 15 '17 at 07:29

simonzack

You could also use, `Object.assign`. Like, `let obj = {a: 1} obj = Object.assign(obj, condition ? {b:1} : {})` – Rajaprabhu Aravindasamy Jan 15 '17 at 07:33
Thanks for the suggestion, but it's more or less the same and a lot longer. – simonzack Jan 15 '17 at 07:33
1

@simonzack yeah except spread syntax for objects is still just a proposal. – Mulan Jan 15 '17 at 07:40
Is there a relationship between `condition` and the key `'b'`? Is there a particular nature to the object that could help inform the decision. To me the first version is perfectly readable. – GantTheWanderer Jan 15 '17 at 07:42
@GantTheWanderer Not really. Indeed the first version is readable enough but I find myself doing this quite often in my code that a very short one would be nice. – simonzack Jan 15 '17 at 07:46
@RajaprabhuAravindasamy Thanks, good find, the second answer helped! – simonzack Jan 15 '17 at 08:01

0 Answers0