urlencode 实现

function urlencode(clearString) {
    var output = ‘‘;
    var x = 0;

    clearString = utf16to8(clearString.toString());
    var regex = /(^[a-zA-Z0-9-_.]*)/;

    while (x < clearString.length) {
        var match = regex.exec(clearString.substr(x));
        if (match != null && match.length > 1 && match[1] != ‘‘) {
            output += match[1];
            x += match[1].length;
        } else {
            if (clearString[x] == ‘ ‘) {
                output += ‘+‘;
            } else {
                var charCode = clearString.charCodeAt(x);
                var hexVal = charCode.toString(16);
                output += ‘%‘ + ( hexVal.length < 2 ? ‘0‘ : ‘‘ ) + hexVal.toUpperCase();
            }
            x++;
        }
    }
    return output;
}

function utf16to8(str) {
    var out, i, len, c;
    out = "";
    len = str.length;
    for(i = 0; i < len; i++) {
        c = str.charCodeAt(i);
        if ((c >= 0x0001) && (c <= 0x007F)) {
            out += str.charAt(i);
        } else if (c > 0x07FF) {
            out += String.fromCharCode(0xE0 | ((c >> 12) & 0x0F));
            out += String.fromCharCode(0x80 | ((c >> 6) & 0x3F));
            out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));
        } else {
            out += String.fromCharCode(0xC0 | ((c >> 6) & 0x1F));
            out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));
        }
    }
    return out;
}