Comments on: Javascript cloning objects

By: Mikael Grave

Mikael Grave — Fri, 09 May 2008 17:29:52 +0000

Your eval/uneval idea inspired me a cross-browser solution for those using YUI:

function clone = function( obj ) {
return YAHOO.lang.JSON.parse( YAHOO.lang.JSON.stringify( obj ) );
}

Tested fine with IE6 and FF2. Especially convenient for cloning arrays, hashs of arrays, arrays of hashs, etc.

Not sure about the performances. Might slow down your app if used to massively clone objects…

By: kymin

kymin — Sun, 20 Apr 2008 18:38:10 +0000

Have you not about c & c++ ’s book ?
Post my E-mail,thank you

By: Gareth Heyes

Gareth Heyes — Thu, 10 Apr 2008 17:19:09 +0000

@kourge

Nice tip and good point

By: kourge

kourge — Thu, 10 Apr 2008 17:08:44 +0000

It is bad practice to mingle with Object.prototype because it messes up property enumeration. Just google “Object.prototype is verboten” and a zillion arguments will appear. The Prototype JavaScript library once did this in 1.3 - with bad results.
The fix is to instead tack methods on to the global Object. For example:
Object.clone = function(object) { return eval(uneval(object)); };

By: Gareth Heyes

Gareth Heyes — Thu, 10 Apr 2008 12:43:31 +0000

@pdp

Damn I thought it worked in IE7 ah well neat trick anyways

By: pdp

pdp — Thu, 10 Apr 2008 11:05:58 +0000

of course that works with FF and a few other browsers only. The more universal way of doing the same is exactly what I used in CoreAPI: http://www.gnucitizen.org/projects/coreapi/

CoreAPI.clone = function (o) {
function c(o) {
for (var i in o) {
this[i] = o[i];
}
}

return new c(o);
};

By: Hakan Bilgin

Hakan Bilgin — Thu, 10 Apr 2008 09:54:16 +0000

Hi Gareth,
Great tips! Unfortunately, if the object contains a reference to an HTML or XML element, those references is not cloned (of course). Which in turn makes this solution a little inadequate.

Yet, thanx for the trick!