前端emijo表情转码解码

      //表情转码
      utf16toEntities(str) {
            var patt=/[\ud800-\udbff][\udc00-\udfff]/g;
            // 检测utf16字符正则
            str = str.replace(patt, function(char){
                var H, L, code;
                if (char.length===2) {
                    H = char.charCodeAt(0);
                    // 取出高位
                    L = char.charCodeAt(1);
                    // 取出低位
                    code = (H - 0xD800) * 0x400 + 0x10000 + L - 0xDC00;
                    // 转换算法
                    var ss = "&#" + code + ";";
                    return ss;
                } else {
                    return char;
                }
            });
            return str;
        },

    //表情解码
     uncodeUtf16(str){
            var reg = /\&#.*?;/g;
            var result = str.replace(reg,function(char){
                var H,L,code;
                if(char.length == 9 ){
                    code = parseInt(char.match(/[0-9]+/g));
                    H = Math.floor((code-0x10000) / 0x400)+0xD800;
                    L = (code - 0x10000) % 0x400 + 0xDC00;
                    return unescape("%u"+H.toString(16)+"%u"+L.toString(16));
                }else{
                    return char;
                }
            });
            return result;
        }