Run results for: Sparse array vs Map for random access and iteration

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/132.0.0.0 Safari/537.36

Browser: Chrome 132

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

Iterate array

2.6M/s

Get from map (all hits)

1.3M/s

Get from array (all hits)

1.1M/s

Iterate map

654K/s

Get from map (with misses)

611K/s

Get from array (with misses)

564K/s

View exact numbers

Test name	Executions per second
✓ Iterate array	2,568,607 Ops/sec
Get from map (all hits)	1,289,440 Ops/sec
Get from array (all hits)	1,087,596 Ops/sec
Iterate map	654,443 Ops/sec
Get from map (with misses)	610,679 Ops/sec
Get from array (with misses)	564,110 Ops/sec

Script Preparation code:

window.indexes = [];
window.arr = [];
window.map = new Map();
for (let i = 0; i < 1000; i++) {
	if (Math.random() > 0.7) {
		window.indexes.push(i);
		window.arr[i] = true;
		window.map.set(i, true);
	}
}

Tests:

Get from array (all hits)
for (const idx of window.indexes) { const a = window.arr[idx]; }
Get from array (with misses)
for (let i = 0; i < 1000; i++) { const a = window.arr[i]; }
Get from map (all hits)
for (const idx of window.indexes) { const a = window.map.get(idx); }
Get from map (with misses)
for (let i = 0; i < 1000; i++) { const a = window.map.get(i); }
Iterate array
for (const val of window.arr) { const a = val; }
Iterate map
for (const val of window.map) { const a = val; }