// This test case check some code frequently used in the wild, with some object // (proxy) for which the optimization we have deployed do not work, as the // assumption the Object.keys(...) can be elided without having noticeable // side-effects. // Similar functions are part of popular framework such as React and Angular. function shallowEqual(o1, o2) { var k1 = Object.keys(o1); var k2 = Object.keys(o2); if (k1.length != k2.length) { return false; } for (var k = 0; k < k1.length; k++) { if (!Object.hasOwnProperty.call(o2, k1[k]) || !Object.is(o1[k1[k]], o2[k1[k]])) { return false; } } return true; } let sideEffectCounter = 0; const payload = {x: 5, a: 1, b: 2, c: 3, d: 4}; const handler = { ownKeys(target) { // side-effect that should not be removed. sideEffectCounter++; // answer returned. return Reflect.ownKeys(target); }, }; const proxy = new Proxy(payload, handler); let objs = [ {x:0, a: 1, b: 2}, {x:1, b: 1, c: 2}, {x:2, c: 1, d: 2}, {x:3, a: 1, b: 2, c: 3}, {x:4, b: 1, c: 2, d: 3}, proxy ]; with({}) {} let iterMax = 1000; for (let i = 0; i < iterMax; i++) { for (let o1 of objs) { for (let o2 of objs) { assertEq(shallowEqual(o1, o2), Object.is(o1, o2)); } } } let expectedSideEffects = 2 * objs.length * iterMax; assertEq(sideEffectCounter, expectedSideEffects);