Run results for: for ++i < length vs .forEach(t) vs for..of vs for t = entries[++i] vs for i = 0; ++i in entries vs for ++i in object vs .reduce (entries)

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:94.0) Gecko/20100101 Firefox/94.0

Browser: Firefox 94

Operating system: Mac OS X 10.15

Device Platform: Desktop

Date tested: 3 years ago

Script Preparation code:

var object = {};
for (let i = 1; i <= 100000; i++) object[String(i)] = i;

Tests:

for i < length
for (let entries = Object.entries(object), i = -1, length = entries.length; ++i < length;) { const t = entries[i]; window.k = t[0] window.v = t[1]; }
.forEach(t)
const entries = Object.entries(object); entries.forEach(([k, v]) => { window.k = k; window.v = v; });
for..of
const entries = Object.entries(object); for (const [k, v] of entries) { window.k = k; window.v = v; }
for t = array[i]
for (let entries = Object.entries(object), i = -1, t; t = entries[++i]; i) { window.k = t[0]; window.v = t[1]; }
for i=0; i in array
for (let entries = Object.entries(object), i = -1; ++i in entries;) { const t = entries[i]; window.k = t[0]; window.v = t[1]; }
for i in array,
for (const k in object) { window.k = k; window.v = object[k]; }
.reduce
const entries = Object.entries(object) entries.reduce((_, [k, v]) => { window.k = k; window.v = v; });