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0 pointspluma10y ago0 comments

I think nearly every JS engine now optimizes `for (...;i < arr.length;...)` -- I'm nearly 100% sure V8 does and fairly certain Firefox's and ModernIE's do as well.

In fact, even `for` is likely an over-optimization. In nearly all JS code you can get away with just using `forEach` (or its friends).

0 comments

thomasfoster9610y ago

forEach is awfully slow compared to a for statement if you're dealing with numbers - less so with strings/objects, but it's still noticeable (like 10x whenever I've tested it at best).

Caching the array length still gives you a small speed boost in most browsers, but it's probably an over optimisation unless you're doing something really intensive.

plumaOP10y ago

If you're doing number crunching, yes, don't use forEach.

If you're just writing ordinary business code (i.e. in 80% of all code out there), by all means, please use forEach and friends.

Besides, if you're doing number crunching in JS, you probably want to stick to ASM.js anyway.

jaredsohn10y ago

I think a big reason to cache the array length within interviews (for cases when it isn't already cached) is that to not do so can often increase the complexity of a solution by a factor of O(n).

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