Run results for: class with/without declared fields

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:122.0) Gecko/20100101 Firefox/122.0

Browser: Firefox 122

Operating system: Mac OS X 10.15

Device Platform: Desktop

Date tested: 2 years ago

Benchmark engine: Benchmark.js

class without declared fields

18K/s

class with declared fields

5K/s

View exact numbers

Test name	Executions per second
✓ class without declared fields	17,663 Ops/sec
class with declared fields	5,372 Ops/sec

Script Preparation code:

// classes declared here can't be accessed in test cases for some reason...

Tests:

class without declared fields
class X { constructor(foo, bar, baz) { this.foo = foo; this.bar = bar; this.baz = baz; } sum() { return this.foo + this.bar + this.baz; } } let i = 1000; let y = 0; while (i--) { let x = new X(1, 2, 3); y += x.foo + x.bar + x.baz; y += x.sum(); } return y;
class with declared fields
class X { foo; bar; baz; constructor(foo, bar, baz) { this.foo = foo; this.bar = bar; this.baz = baz; } sum() { return this.foo + this.bar + this.baz; } } let i = 1000; let y = 0; while (i--) { let x = new X(1, 2, 3); y += x.foo + x.bar + x.baz; y += x.sum(); } return y;