Run results for: WeakMap vs "Symbol with WeakMap fallback"

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:120.0) Gecko/20100101 Firefox/120.0

Browser: Firefox 120

Operating system: Windows

Device Platform: Desktop

Date tested: 2 years ago

Benchmark engine: Benchmark.js

Symbol with WeakMap fallback get

314.2M/s

Symbol with WeakMap fallback set

259.8M/s

WeakMap get

35.0M/s

WeakMap set

19.4M/s

View exact numbers

Test name	Executions per second
✓ Symbol with WeakMap fallback get	314,160,640 Ops/sec
Symbol with WeakMap fallback set	259,768,816 Ops/sec
WeakMap get	35,020,544 Ops/sec
WeakMap set	19,382,890 Ops/sec

Script Preparation code:

var c = Symbol === undefined
? (function() {
  var x = function() {
    this._x = new WeakMap();
  }
  x.prototype.get = function(x) { return this._x.get(x); };
  x.prototype.set = function(x,y) { this._x.set(x,y); };
  return x;
})()
: (function() {
  var x = function() {
    this._x = Symbol();
  }
  x.prototype.get = function(x) { return x[this._x]; };
  x.prototype.set = function(x,y) { x[this._x] = y; };
  return x;
})();

var to0 = {};
var to1 = {};
var wm = new WeakMap();
var fwm = new c();
wm.set(to1, 1);
fwm.set(to1, 1);

Tests:

WeakMap get
let r = wm.get(to1);
Symbol with WeakMap fallback get
let r = fwm.get(to1);
WeakMap set
wm.set(to0, 1);
Symbol with WeakMap fallback set
fwm.set(to0, 1);