function trim(str, charlist)
{
    // Strips whitespace from the beginning and end of a string  
    // 
    // version: 909.322
    // discuss at: http://phpjs.org/functions/trim    // +   original by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +   improved by: mdsjack (http://www.mdsjack.bo.it)
    // +   improved by: Alexander Ermolaev (http://snippets.dzone.com/user/AlexanderErmolaev)
    // +      input by: Erkekjetter
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)    // +      input by: DxGx
    // +   improved by: Steven Levithan (http://blog.stevenlevithan.com)
    // +    tweaked by: Jack
    // +   bugfixed by: Onno Marsman
    // *     example 1: trim('    Kevin van Zonneveld    ');    // *     returns 1: 'Kevin van Zonneveld'
    // *     example 2: trim('Hello World', 'Hdle');
    // *     returns 2: 'o Wor'
    // *     example 3: trim(16, 1);
    // *     returns 3: 6    var whitespace, l = 0, i = 0;
    str += '';
    var whitespace;
    if (!charlist) {
        whitespace = " \n\r\t\f\x0b\xa0\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200a\u200b\u2028\u2029\u3000";
    } else {
        // preg_quote custom list
        charlist += '';
        whitespace = charlist.replace(/([\[\]\(\)\.\?\/\*\{\}\+\$\^\:])/g, '$1');    }
    
    l = str.length;
    for (i = 0; i < l; i++) {
        if (whitespace.indexOf(str.charAt(i)) === -1) {            str = str.substring(i);
            break;
        }
    }
        l = str.length;
    for (i = l - 1; i >= 0; i--) {
        if (whitespace.indexOf(str.charAt(i)) === -1) {
            str = str.substring(0, i + 1);
            break;        }
    }
    
    return whitespace.indexOf(str.charAt(0)) === -1 ? str : '';
}