function encodeURL(str){

    var s0, i, s, u;

    s0 = "";                // encoded str

    for (i = 0; i < str.length; i++){   // scan the source

        s = str.charAt(i);

        u = str.charCodeAt(i);          // get unicode of the char

        if (s == " "){s0 += "+";}       // SP should be converted to "+"

        else {

            if ( u == 0x2a || u == 0x2d || u == 0x2e || u == 0x5f || ((u >= 0x30) && (u <= 0x39)) || ((u >= 0x41) && (u <= 0x5a)) || ((u >= 0x61) && (u <= 0x7a))){       // check for escape

                s0 = s0 + s;            // don't escape

            }

            else {                  // escape

                if ((u >= 0x0) && (u <= 0x7f)){     // single byte format

                    s = "0"+u.toString(16);

                    s0 += "%"+ s.substr(s.length-2);

                }

                else if (u > 0x1fffff){     // quaternary byte format (extended)

                    s0 += "%" + (oxf0 + ((u & 0x1c0000) >> 18)).toString(16);

                    s0 += "%" + (0x80 + ((u & 0x3f000) >> 12)).toString(16);

                    s0 += "%" + (0x80 + ((u & 0xfc0) >> 6)).toString(16);

                    s0 += "%" + (0x80 + (u & 0x3f)).toString(16);

                }

                else if (u > 0x7ff){        // triple byte format

                    s0 += "%" + (0xe0 + ((u & 0xf000) >> 12)).toString(16);

                    s0 += "%" + (0x80 + ((u & 0xfc0) >> 6)).toString(16);

                    s0 += "%" + (0x80 + (u & 0x3f)).toString(16);

                }

                else {                      // double byte format

                    s0 += "%" + (0xc0 + ((u & 0x7c0) >> 6)).toString(16);

                    s0 += "%" + (0x80 + (u & 0x3f)).toString(16);

                }

            }

        }

    }

    return s0;

}