/* * Don't throw a type error if the trap reports an undefined property as * non-present, regardless of extensibility. */ var target = {}; Object.preventExtensions(target); var handler = { has: () => false }; for (let p of [new Proxy(target, handler), Proxy.revocable(target, handler).proxy]) { assertEq('foo' in p, false); assertEq(Symbol.iterator in p, false); }