how to make a variable of a nested object key

Question

If I have the following code written where i'm trying to interchange between failedIds and passedIds:

hideShowTestResults: function(failOrPass){
    if(this.[failOrPass ? passedIds : failedIds ].length > 0){} 
}

Yet this syntax is not accepted in JS, how would I go about this?

Thanks, Bud

The object accessor required a `string` value, and after that you probably should not access `failedIds` once again. ALSO you should avoid `.` (dot) between this and the bracket — Markiian Benovskyi, Dec 05 '19 at 15:07
Refer to [this answer](https://stackoverflow.com/a/6084875/11907346) in a similar question. — Clint Winter, Dec 05 '19 at 15:08
Unrelated, but when there's "multi-level" logic like this it's almost always better to pull it out into a temp var and make the code that much easier to reason about. — Dave Newton, Dec 05 '19 at 15:09
`failOrPass` is a boolean variable? You shouldn't call it that if it is. — TKoL, Dec 05 '19 at 15:11

score 6 · Accepted Answer · answered Dec 05 '19 at 15:09

6

if (this[failOrPass ? 'passedIds' : 'failedIds'].length > 0) {

Or, because selecting a property name is kind of less readable than selecting an array:

if ((failOrPass ? this.passedIds : this.failedIds).length > 0) {

answered Dec 05 '19 at 15:09

Ry-

This seems like a weird function, though. It might be better as two or more functions. – Ry- Dec 05 '19 at 15:10
Noting that it'd be more readable, and reduce cognitive overhead, to pull this out into two statements. – Dave Newton Dec 05 '19 at 15:11
1

I just did now : `let result = failOrPass ? this.passedIds : this.failedIds;` and then: `if(result.length > 0){}` but you answer is well invested, so i'll vote it soon when it allows – senseCode Dec 05 '19 at 15:13

1 Answers1