Run results for: Map() delete while iterating vs clear

When iterating over a Map and clearing after iteration is required, is it faster to remove items at each iteration step or is it faster to iterate and then clear() the entire Map afterwards?

Run details:

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Mobile Safari/537.36

Browser: Chrome Mobile 122

Operating system: Android

Device Platform: Mobile

Date tested: 2 years ago

Benchmark engine: Benchmark.js

Iterate + delete

7.2M/s

Iterate + clear

2.6M/s

View exact numbers

Test name	Executions per second
✓ Iterate + delete	7,247,822 Ops/sec
Iterate + clear	2,583,367 Ops/sec

Script Preparation code:

var dummy = 0;
var map = new Map(new Array(100).fill(null).map((_, i) => [
  function(incrementBy) {
  	dummy += incrementBy;
  },
  { incrementBy: i }
]));

Tests:

Iterate + clear
for (const [fn, obj] of map) { fn(obj.incrementBy); } map.clear();
Iterate + delete
for (const [fn, obj] of map) { fn(obj.incrementBy); map.delete(fn); }