> 2- avoid using the functional primitives like map
I understand that map requires creating a new array, and that is already included in point 1. What overhead are functional primitives subject to apart from memory allocation? e.g. forEach
I understand that map requires creating a new array, and that is already included in point 1. What overhead are functional primitives subject to apart from memory allocation? e.g. forEach
BTW, it's easy to test the basic primitives. I use Chrome snippets.
test = (name, fn) => {
const timeLimitMs = 1000
let start = Date.now(), count = 0
while (Date.now() - start < timeLimitMs) { fn(); count++ }
console.log(name, count)
}
var N = 1000000
let a = new Array(N)
test('for loop', _=> { for (var i = 0; i < N; i++) a[i] = i })
test('map', _=> { a = a.map((x,i) => i) })
test('forEach', _=> { a.forEach((v,i,a) => a[i] = i) })
for loop 941
map 37
forEach 69
Like so?
const N = 1000000
let a = new Array(N), b = new Array(N)
for (let i = 0; i < N; i++) a[i] = i
test('copy loop', _=> { for (var i = 0; i < N; i++) b[i] = a[i] })
test('copy map', _=> { b = a.map((x,i) => a[i]) })
test('copy forEach', _=> { a.forEach((v,i,a) => b[i] = a[i]) })
Are you using a different browser? I know that sometimes other browsers have very different results.
In any case, it's somewhat irrelevant if there are cases that optimize and cases that don't. When idiomatic functional code is sometimes up to 30x slower than a for loop, it can't be used in perf critical sections. Even if it's only Chrome and only certain cases. The forEach perf needs to be always reliably performant before I can use it without worry.