Checking for an empty array can be faster
inoyakaigor opened this issue · 5 comments
I made a simple performance test and it shows that getting length of array keys is not optimal code. I propose change it to a.filter(Boolean).length > 0. This code can be faster from 4.5 (Firefox) or 5.9 (Chrome) to 26 (Safari) times.
Hey Igor, that is a really good insight.
However, as you probably know, this is not universal. There could be valid falsy values in the array, like ['', 0]. Which this would mark as empty.
However, seeing how fast a.lenght is, maybe it makes sense to add this before the keys check, WDYT?
Yeah, exactly, falsy. How I could forget!
I think there is still need filter function and therefore I suppose better solution wich cover edge cases is
Array.isArray(a) && a.length > 0 && a.filter(el => el === undefined)Also checking can be faster if use latest ES2020 feature (link):
For history: my jsperf test from initial message https://jsperf.com/object-keys-vs-array-length
Can you make a PR?
Yes of course