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?

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Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:134.0) Gecko/20100101 Firefox/134.0

Browser: Firefox 134

Operating system: Mac OS X 10.15

Device Platform: Desktop

Date tested: one year ago

Benchmark engine: Benchmark.js

Iterate + delete

25.4M/s

Iterate + clear

20.8M/s

View exact numbers

Test name	Executions per second
✓ Iterate + delete	25,416,440 Ops/sec
Iterate + clear	20,802,818 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); }