Variable serialiser

/****************************************************************************************
                        Script to serialise variable data
                     Written by Mark Wilton-Jones, 22/05/2005
 V1.1 updated 30/05/2005 to remove a Safari/IEMac bug, and hide new methods until needed
*****************************************************************************************

Please see http://www.howtocreate.co.uk/jslibs/ for details and a demo of this script
Please see http://www.howtocreate.co.uk/jslibs/termsOfUse.html for terms of use

This script can serialise strings, numbers, boolean values, regular expressions, date objects,
and even objects, arrays, and functions into a valid string. This can then be saved into a
cookie (with the 4KB cookie limitation), or evaluated back into a valid variable, replicating
the original variable structure. There are a few limitations;

 - DOM nodes are not serialised (represented as {error:'DOM node'} or {error:'internal object'})
 - Arrays can either have indexes, or key/values, not both
 - Arrays using only key/values are represented as objects
 - Cyclic references are not allowed, and will be automatically removed (represented as ['LoopBack'] or {'LoopBack'})
 - Internal functions cannot be referenced (represented as function () {['native code']})
 - Using numeric strings ('00') as object property names is not possible (they will be treated as numbers)
 - Safari will corrupt big functions

To use:
_________________________________________________________________________

Inbetween the <head> tags, put:

<script src="PATH TO SCRIPT/recoverablestring.js" type="text/javascript" language="javascript"></script>

To serialise variables, use:

var variableString = getRecoverableString( originalVariable );

To recover variables, use:

eval('var newVariable = '+variableString);
_______________________________________________________________________________________*/

/* why the mix of functions and methods?
 - the function cannot tell the difference between an object, an array, and null
   because typeof says they are all objects, so arrays would be corrupted
 - null and undefined cannot have methods and would produce errors */

function getRecoverableString(oVar,notFirst) {
	var oType = typeof(oVar);
	if( ( oType == 'null' ) || ( oType == 'object' && !oVar ) ) {
		//most browsers say that the typeof for null is 'object', but unlike a real
		//object, it will not have any overall value
		return 'null';
	}
	if( oType == 'undefined' ) { return 'window.uDfXZ0_d'; }
	if( oType == 'object' ) {
		//Safari throws errors when comparing non-objects with window/document/etc
		if( oVar == window ) { return 'window'; }
		if( oVar == document ) { return 'document'; }
		if( oVar == document.body ) { return 'document.body'; }
		if( oVar == document.documentElement ) { return 'document.documentElement'; }
	}
	if( oVar.nodeType && ( oVar.childNodes || oVar.ownerElement ) ) { return '{error:\'DOM node\'}'; }
	if( !notFirst ) {
		Object.prototype.toRecoverableString = function (oBn) {
			if( this.tempLockIgnoreMe ) { return '{\'LoopBack\'}'; }
			this.tempLockIgnoreMe = true;
			var retVal = '{', sepChar = '', j;
			for( var i in this ) {
				if( i == 'toRecoverableString' || i == 'tempLockIgnoreMe' || i == 'prototype' || i == 'constructor' ) { continue; }
				if( oBn && ( i == 'index' || i == 'input' || i == 'length' || i == 'toRecoverableObString' ) ) { continue; }
				j = this[i];
				if( !i.match(basicObPropNameValStr) ) {
					//for some reason, you cannot use unescape when defining property names inline
					for( var x = 0; x < cleanStrFromAr.length; x++ ) {
						i = i.replace(cleanStrFromAr[x],cleanStrToAr[x]);
					}
					i = '\''+i+'\'';
				} else if( window.ActiveXObject && navigator.userAgent.indexOf('Mac') + 1 && !navigator.__ice_version && window.ScriptEngine && ScriptEngine() == 'JScript' && i.match(/^\d+$/) ) {
					//IE mac does not allow numerical property names to be used unless they are quoted
					i = '\''+i+'\'';
				}
				retVal += sepChar+i+':'+getRecoverableString(j,true);
				sepChar = ',';
			}
			retVal += '}';
			this.tempLockIgnoreMe = false;
			return retVal;
		};
		Array.prototype.toRecoverableObString = Object.prototype.toRecoverableString;
		Array.prototype.toRecoverableString = function () {
			if( this.tempLock ) { return '[\'LoopBack\']'; }
			if( !this.length ) {
				var oCountProp = 0;
				for( var i in this ) { if( i != 'toRecoverableString' && i != 'toRecoverableObString' && i != 'tempLockIgnoreMe' && i != 'prototype' && i != 'constructor' && i != 'index' && i != 'input' && i != 'length' ) { oCountProp++; } }
				if( oCountProp ) { return this.toRecoverableObString(true); }
			}
			this.tempLock = true;
			var retVal = '[';
			for( var i = 0; i < this.length; i++ ) {
				retVal += (i?',':'')+getRecoverableString(this[i],true);
			}
			retVal += ']';
			delete this.tempLock;
			return retVal;
		};
		Boolean.prototype.toRecoverableString = function () {
			return ''+this+'';
		};
		Date.prototype.toRecoverableString = function () {
			return 'new Date('+this.getTime()+')';
		};
		Function.prototype.toRecoverableString = function () {
			return this.toString().replace(/^\s+|\s+$/g,'').replace(/^function\s+[^\(]*\(/g,'function (').replace(/^function\s*\w*\([^\)]*\)\s*\{\s*\[native\s+code\]\s*\}$/i,'function () {[\'native code\'];}');
		};
		Number.prototype.toRecoverableString = function () {
			if( isNaN(this) ) { return 'Number.NaN'; }
			if( this == Number.POSITIVE_INFINITY ) { return 'Number.POSITIVE_INFINITY'; }
			if( this == Number.NEGATIVE_INFINITY ) { return 'Number.NEGATIVE_INFINITY'; }
			return ''+this+'';
		};
		RegExp.prototype.toRecoverableString = function () {
			return '\/'+this.source+'\/'+(this.global?'g':'')+(this.ignoreCase?'i':'');
		};
		String.prototype.toRecoverableString = function () {
			var oTmp = escape(this);
			if( oTmp == this ) { return '\''+this+'\''; }
			return 'unescape(\''+oTmp+'\')';
		};
	}
	if( !oVar.toRecoverableString ) { return '{error:\'internal object\'}'; }
	var oTmp = oVar.toRecoverableString();
	if( !notFirst ) {
		//prevent it from changing for...in loops that the page may be using
		delete Object.prototype.toRecoverableString;
		delete Array.prototype.toRecoverableObString;
		delete Array.prototype.toRecoverableString;
		delete Boolean.prototype.toRecoverableString;
		delete Date.prototype.toRecoverableString;
		delete Function.prototype.toRecoverableString;
		delete Number.prototype.toRecoverableString;
		delete RegExp.prototype.toRecoverableString;
		delete String.prototype.toRecoverableString;
	}
	return oTmp;
}
var basicObPropNameValStr = /^\w+$/, cleanStrFromAr = new Array(/\\/g,/'/g,/"/g,/\r/g,/\n/g,/\f/g,/\t/g,new RegExp('-'+'->','g'),new RegExp('<!-'+'-','g'),/\//g), cleanStrToAr = new Array('\\\\','\\\'','\\\"','\\r','\\n','\\f','\\t','-\'+\'->','<!-\'+\'-','\\\/');