<p>This page tests whether primitive conversions during equality tests properly throw exceptions. If the test passes, you'll see a series of PASS messages below. </p> <hr> <pre id="console"></pre> <script> function log(s) { document.getElementById("console").appendChild(document.createTextNode(s + "\n")); } function shouldThrow(expression, exception, didCorrectlyThrow) { if (didCorrectlyThrow) log("PASS: " + expression + " should throw a " + exception + ", and did."); else log("FAIL: " + expression + " should throw a " + exception + ", but didn't."); } if (window.testRunner) testRunner.dumpAsText(); var o = { valueOf: function() { return { }; // should throw, because this is not a primitive value }, toString: function() { return { }; // should throw, because this is not a primitive value } }; shouldThrow("o == 'a'", "type error", (function() { try { o == 'a'; return false; } catch(e) { return e instanceof TypeError; } })()); shouldThrow("o != 'a'", "type error", (function() { try { o != 'a'; return false; } catch(e) { return e instanceof TypeError; } })()); shouldThrow("o == 0", "type error", (function() { try { o == 'a'; return false; } catch(e) { return e instanceof TypeError; } })()); shouldThrow("o != 0", "type error", (function() { try { o != 'a'; return false; } catch(e) { return e instanceof TypeError; } })()); </script>