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isPlainObject
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| <!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> | |
| var toString = Object.prototype.toString; | |
| var hasOwnProperty = Object.prototype.hasOwnProperty; | |
| function isObjectLiteral(obj){ | |
| if ( toString.call(obj) !== "[object Object]" || typeof obj.nodeType === "number" ) { | |
| return false; | |
| } | |
| // not own constructor property must be Object | |
| if ( obj.constructor | |
| && !hasOwnProperty.call(obj, "constructor") | |
| && !hasOwnProperty.call(obj.constructor.prototype, "isPrototypeOf") ) { | |
| return false; | |
| } | |
| //own properties are iterated firstly, | |
| //so to speed up, we can test last one if it is own or not | |
| var key; | |
| for ( key in obj ) {} | |
| return key === undefined || hasOwnProperty.call( obj, key ); | |
| } | |
| // Function serialization is not permitted | |
| // Does not work across all browsers | |
| Function.prototype.toString = function(){}; | |
| // The use case that we want to match | |
| log("{}", {}, true); | |
| // Instantiated objects shouldn't be matched | |
| log("new Date", new Date, false); | |
| var fn = function(){}; | |
| // Functions shouldn't be matched | |
| log("fn", fn, false); | |
| // Again, instantiated objects shouldn't be matched | |
| log("new fn (no methods)", new fn, false); | |
| // Makes the function a little more realistic | |
| // (and harder to detect, incidentally) | |
| fn.prototype = {someMethod: function(){}}; | |
| // Again, instantiated objects shouldn't be matched | |
| log("new fn", new fn, false); | |
| log("div", document.createElement("div"), false ); | |
| /* Note: | |
| * The restriction against instantiated functions is | |
| * due to the fact that this method will be used for | |
| * deep-cloning an object. Instantiated objects will | |
| * just have their reference copied over, whereas | |
| * plain objects will need to be completely cloned. | |
| */ | |
| 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){ | |
| // Objects from other windows should be matched | |
| 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> |
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