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LibJS: Implicitly break for..in loop if the RHS result is nullish

This implements the missing step 6a of 14.7.5.6 ForIn/OfHeadEvaluation:

    a. If exprValue is undefined or null, then
        i. Return Completion { [[Type]]: break, [[Value]]: empty, [[Target]]: empty }.

In other words, this should just do nothing instead of throwing during
the undefined to object coercion:

    for (const x in undefined);
This commit is contained in:
Linus Groh 2021-04-10 18:47:18 +02:00 committed by Andreas Kling
parent 9cd010167a
commit 2172e51246
2 changed files with 8 additions and 0 deletions

View file

@ -38,6 +38,12 @@ test("iterate through object", () => {
expect(a).toEqual(["a", "b", "c"]);
});
test("iterate through undefined", () => {
for (const property in undefined) {
expect.fail();
}
});
test("use already-declared variable", () => {
var property;
for (property in "abc");