function urlencode (str)
{
    str = (str+'').toString();
    
    // Tilde should be allowed unescaped in future versions of PHP (as reflected below), but if you want to reflect current
    // PHP behavior, you would need to add ".replace(/~/g, '%7E');" to the following.
    return encodeURIComponent(str).replace(/!/g, '%21').replace(/'/g, '%27').replace(/\(/g, '%28').replace(/\)/g, '%29').replace(/\*/g, '%2A').replace(/%20/g, '+');
}