// The receiver argument is passed through proxies with no "set" handler. var hits; var a = new Proxy({}, { set(t, id, value, receiver) { assertEq(id, "prop"); assertEq(value, 3); assertEq(receiver, b); hits++; } }); var b = new Proxy(a, {}); hits = 0; b.prop = 3; assertEq(hits, 1);