22e1df58d3
The delete operator needs the Reference produced by an optional chain when the chain ends in a property access. We evaluated the chain for side effects and returned true, so delete object?.property reported success without removing the property. Emit delete-specific optional-chain bytecode. It short-circuits to true for nullish optional hops, but performs DeleteById or DeleteByValue when the final property reference is reached. Add runtime coverage for named, computed, and short-circuited optional deletes.
54 lines
1.5 KiB
JavaScript
54 lines
1.5 KiB
JavaScript
test("parse optional-chaining", () => {
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expect(`a?.b`).toEval();
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expect(`a?.4:.5`).toEval();
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expect(`a?.[b]`).toEval();
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expect(`a?.b[b]`).toEval();
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expect(`a?.b(c)`).toEval();
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expect(`a?.b?.(c, d)`).toEval();
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expect(`a?.b?.()`).toEval();
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expect("a?.b``").not.toEval();
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expect("a?.b?.``").not.toEval();
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expect("new Foo?.bar").not.toEval();
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expect("new (Foo?.bar)").toEval();
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expect("(new Foo)?.bar").toEval();
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});
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test("evaluate optional-chaining", () => {
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for (let nullishObject of [null, undefined]) {
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expect((() => nullishObject?.b)()).toBeUndefined();
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}
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expect(
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(() => {
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let a = {};
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return a?.foo?.bar?.baz;
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})()
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).toBeUndefined();
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expect(
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(() => {
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let a = { foo: { bar: () => 42 } };
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return `${a?.foo?.bar?.()}-${a?.foo?.baz?.()}`;
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})()
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).toBe("42-undefined");
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expect(() => {
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let a = { foo: { bar: () => 42 } };
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return a.foo?.baz.nonExistentProperty;
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}).toThrow();
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});
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test("delete optional-chaining property references", () => {
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let object = { value: 1, computed: 2 };
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expect(delete object?.value).toBeTrue();
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expect(object.value).toBeUndefined();
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expect(delete object?.["computed"]).toBeTrue();
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expect(object.computed).toBeUndefined();
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let keyEvaluations = 0;
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expect(delete undefined?.[keyEvaluations++]).toBeTrue();
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expect(keyEvaluations).toBe(0);
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expect(delete { inner: null }?.inner?.value).toBeTrue();
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});
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