function urlencode (str) {
    // http://kevin.vanzonneveld.net
    // +   original by: Philip Peterson
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +      input by: AJ
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // %          note: info on what encoding functions to use from: http://xkr.us/articles/javascript/encode-compare/                                     
    var histogram = {}, histogram_r = {}, code = 0, tmp_arr = [];
    var ret = str.toString();
    
    var replacer = function(search, replace, str) {
        var tmp_arr = [];
        tmp_arr = str.split(search);
        return tmp_arr.join(replace);
    };
    
    // The histogram is identical to the one in urldecode.
    histogram['!']   = '%21';
    histogram['%20'] = '+';
    
    // Begin with encodeURIComponent, which most resembles PHP's encoding functions
    ret = encodeURIComponent(ret);
    
    for (search in histogram) {
        replace = histogram[search];
        ret = replacer(search, replace, ret) // Custom replace. No regexing
    }
    
    // Uppercase for full PHP compatibility
    return ret.replace(/(\%([a-z0-9]{2}))/g, function(full, m1, m2) {
        return "%"+m2.toUpperCase();
    });
    
    return ret;
}