function f(arr) { assertEq(arr.push(4), 5); // if it doesn't throw :-) } function test(out) { // Create an array of arrays, to be iterated over for [].push-calling. We // can't just loop on push on a single array with non-writable length because // push throws when called on an array with non-writable length. var arrs = out.arrs = []; for (var i = 0; i < 100; i++) arrs.push([0, 1, 2, 3]); // Use a much-greater capacity than the eventual non-writable length, so that // the inline-push will work. var a = [0, 1, 2, 3, 4, 5, 6, 7]; Object.defineProperty(a, "length", { writable: false, value: 4 }); arrs.push(a); for (var i = 0, sz = arrs.length; i < sz; i++) { var arr = arrs[i]; f(arr); } } var obj = {}; var a, arrs; try { test(obj); throw new Error("didn't throw!"); } catch (e) { assertEq(e instanceof TypeError, true, "expected TypeError, got " + e); arrs = obj.arrs; assertEq(arrs.length, 101); for (var i = 0; i < 100; i++) { assertEq(arrs[i].length, 5, "unexpected length for arrs[" + i + "]"); assertEq(arrs[i][0], 0, "bad element for arrs[" + i + "][0]"); assertEq(arrs[i][1], 1, "bad element for arrs[" + i + "][1]"); assertEq(arrs[i][2], 2, "bad element for arrs[" + i + "][2]"); assertEq(arrs[i][3], 3, "bad element for arrs[" + i + "][3]"); assertEq(arrs[i][4], 4, "bad element for arrs[" + i + "][4]"); } a = arrs[100]; assertEq(a[0], 0, "bad element for a[" + i + "]"); assertEq(a[1], 1, "bad element for a[" + i + "]"); assertEq(a[2], 2, "bad element for a[" + i + "]"); assertEq(a[3], 3, "bad element for a[" + i + "]"); assertEq(a.hasOwnProperty(4), false, "element addition should have thrown"); assertEq(a[4], undefined); assertEq(a.length, 4, "length shouldn't have been changed"); }