Run results for: init on demand vs at the beginning

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/18.4 Safari/605.1.15

Browser: Safari 18

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
includes	188384832.0 Ops/sec
lookup	649772160.0 Ops/sec

Script Preparation code:

function a(arr) {
  let kinds;
  return (node) => {
    kinds ??= new Set(arr);
    return kinds.has(node.kind);
  };
}

function b(arr) {
  const kinds = new Set(arr);
  return (node) => kinds.has(node.kind);
}
const c = a([1, 2, 3]);
const d = b([1, 2, 3]);

Tests:

includes
return c({kind: 1});
lookup
return d({kind: 1});

Run results for: init on demand vs at the beginning

includes

lookup