js的utf16编码 emoji

从js传输到服务器的时候这么编码了
stringToUTF8Bytes = function(str) { var utf8 = []; for (var i=0; i < str.length; i++) { var charcode = str.charCodeAt(i); if (charcode < 0x80) utf8.push(charcode); else if (charcode < 0x800) { utf8.push(0xc0 | (charcode >> 6), 0x80 | (charcode & 0x3f)); } else if (charcode < 0xd800 || charcode >= 0xe000) { utf8.push(0xe0 | (charcode >> 12), 0x80 | ((charcode>>6) & 0x3f), 0x80 | (charcode & 0x3f)); } // surrogate pair else { i++; // UTF-16 encodes 0x10000-0x10FFFF by // subtracting 0x10000 and splitting the // 20 bits of 0x0-0xFFFFF into two halves charcode = 0x10000 + (((charcode & 0x3ff)<<10) | (str.charCodeAt(i) & 0x3ff)) utf8.push(0xf0 | (charcode >>18), 0x80 | ((charcode>>12) & 0x3f), 0x80 | ((charcode>>6) & 0x3f), 0x80 | (charcode & 0x3f)); } } return utf8; }
回来的时候
`utf8ArrayToString = function(array)
{
var out, i, len, c;
var char2, char3;

out = "";
len = array.length;
i = 0;

while(i < len)
{
    c = array[i++];

    switch(c >> 4)
    {
        case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:
        // 0xxxxxxx
        out += String.fromCharCode(c);
        break;
        case 12: case 13:
        // 110x xxxx   10xx xxxx
        char2 = array[i++];
        out += String.fromCharCode(((c & 0x1F) << 6) | (char2 & 0x3F));
        break;
        case 14:
            // 1110 xxxx  10xx xxxx  10xx xxxx
            char2 = array[i++];
            char3 = array[i++];
            out += String.fromCharCode(((c & 0x0F) << 12) |
                ((char2 & 0x3F) << 6) |
                ((char3 & 0x3F) << 0));
            break;
    }
}

return out;

}`emoji数据没有正确还原了 有什么好的办法么