kangax · July 23, 2009 17:43
diff --git a/isObjectLiteral.html b/isObjectLiteral.html
 /*

 Checks that `toString` of constructor's prototype has "special" behavior (i.e. is `Object.prototype.toString`) as per 15.2.4.2

 Cons: 
    - Relies on `constructor` property of an object (as well as `toString` of constructor's prototype) being present and not augmented
      (will fail on host objects in IE that lack constructor, but could be guarded against)
    - Does not differentiate between Object objects created implicitly via function constructor and those created explicitly via Object

 Pros:
    - Does not rely on func. decomp.
    - Should work across windows and in any ES3 compliant implementation

 */
 <!DOCTYPE html>
 <html>
 <head>
        <meta http-equiv="content-type" content="text/html;charset=utf-8"/>
        <!-- Online here: http://ejohn.org/files/bugs/isObjectLiteral/ -->
        <title>isObjectLiteral</title>
        <style>
        li { background: green; } li.FAIL { background: red; }
        iframe { display: none; }
        </style>
 </head>
 <body>
 <ul id="results"></ul>
 <script>

 function isObjectLiteral(obj) {
  var _toString = obj.constructor.prototype.toString;
  try {
    return _toString.call([]) === '[object Array]';
  } catch(e) {
    return false;
  }
 }

 // Function serialization is not permitted
 // Does not work across all browsers
 Function.prototype.toString = function(){};

 log("{}", {}, true);
 log("new Date", new Date, false);

 var fn = function(){};
 log("fn", fn, false);
 log("new fn", new fn, false);

 var iframe = document.createElement("iframe");
 document.body.appendChild(iframe);

 var doc = iframe.contentDocument || iframe.contentWindow.document;
 doc.open();
 doc.write("<body onload='window.top.iframeDone(Object);'>");
 doc.close();

 function iframeDone(otherObject){
        log("new otherObject", new otherObject, true);
 }

 function log(msg, a, b) {
  var pass = isObjectLiteral(a) === b ? "PASS" : "FAIL";

  document.getElementById("results").innerHTML +=
        "<li class='" + pass + "'>" + msg + "</li>";
 }
 </script>
 </body>
 </html>
	/*

	Checks that `toString` of constructor's prototype has "special" behavior (i.e. is `Object.prototype.toString`) as per 15.2.4.2

	Cons:
	- Relies on `constructor` property of an object (as well as `toString` of constructor's prototype) being present and not augmented
	(will fail on host objects in IE that lack constructor, but could be guarded against)
	- Does not differentiate between Object objects created implicitly via function constructor and those created explicitly via Object

	Pros:
	- Does not rely on func. decomp.
	- Should work across windows and in any ES3 compliant implementation

	*/
	<!DOCTYPE html>
	<html>
	<head>
	<meta http-equiv="content-type" content="text/html;charset=utf-8"/>
	<!-- Online here: http://ejohn.org/files/bugs/isObjectLiteral/ -->
	<title>isObjectLiteral</title>
	<style>
	li { background: green; } li.FAIL { background: red; }
	iframe { display: none; }
	</style>
	</head>
	<body>
	<ul id="results"></ul>
	<script>

	function isObjectLiteral(obj) {
	var _toString = obj.constructor.prototype.toString;
	try {
	return _toString.call([]) === '[object Array]';
	} catch(e) {
	return false;
	}
	}

	// Function serialization is not permitted
	// Does not work across all browsers
	Function.prototype.toString = function(){};

	log("{}", {}, true);
	log("new Date", new Date, false);

	var fn = function(){};
	log("fn", fn, false);
	log("new fn", new fn, false);

	var iframe = document.createElement("iframe");
	document.body.appendChild(iframe);

	var doc = iframe.contentDocument \|\| iframe.contentWindow.document;
	doc.open();
	doc.write("<body onload='window.top.iframeDone(Object);'>");
	doc.close();

	function iframeDone(otherObject){
	log("new otherObject", new otherObject, true);
	}

	function log(msg, a, b) {
	var pass = isObjectLiteral(a) === b ? "PASS" : "FAIL";

	document.getElementById("results").innerHTML +=
	"<li class='" + pass + "'>" + msg + "</li>";
	}
	</script>
	</body>
	</html>