get query variable via js

gistfile1.js

function getParameterByName( name ){
	if( typeof getParameterByName.params == 'undefined' )
		getParameterByName.params = {};
	if( typeof getParameterByName.params[name] == 'undefined' ){
		name = name.replace( /[\[]/, "\\\[" ).replace( /[\]]/, "\\\]" );
		var regex = new RegExp( "[\\?&]" + name + "(?:=([^&#]*))?" ), 
		 results = regex.exec( location.search );
		// if only key was given, assume value is 'true'
		if( results === null )
			getParameterByName.params[name] = null;
		else if( typeof results[1] == 'undefined' )
			getParameterByName.params[name] = true;
		else
			getParameterByName.params[name] =  decodeURIComponent( results[1].replace( /\+/g, " " ) );
	}
	return getParameterByName.params[name];
}