js 编码问题

//字符转换为UTF-8编码
function encutf8(s1) {
         var stringArray = new Array();
         for(var j=0; j<s1.length;j++){
               stringArray[j] = escape(s1.charAt(j)).replace("%",""); 
           }
    
        var sa = stringArray;
        
        var retV = "";
        
        for (var i = 0; i < sa.length; i++) {
            
            if (sa[i].length > 1 && sa[i].substring(0, 1) == "u") {
                retV += Hex2Utf8(Str2Hex(sa[i].substring(1, 5)));
            }else if(sa[i].length == 2){
                //转义字符和标点符号
                retV += "%" + sa[i];
            } else {
                retV += sa[i];                
            }
        }
        return retV;
    }

function Str2Hex(s) {
    var c = "";
    var n;
    var ss = "0123456789ABCDEF";
    var digS = "";
    for (var i = 0; i < s.length; i++) {
        c = s.charAt(i);
        n = ss.indexOf(c);
        digS += Dec2Dig(eval(n));
    }
//return value;
    return digS;
}
function Dec2Dig(n1) {
    var s = "";
    var n2 = 0;
    for (var i = 0; i < 4; i++) {
        n2 = Math.pow(2, 3 - i);
        if (n1 >= n2) {
            s += "1";
            n1 = n1 - n2;
        } else {
            s += "0";
        }
    }
    return s;
}
function Dig2Dec(s) {
    var retV = 0;
    if (s.length == 4) {
        for (var i = 0; i < 4; i++) {
            retV += eval(s.charAt(i)) * Math.pow(2, 3 - i);
        }
        return retV;
    }
    return -1;
}
function Hex2Utf8(s) {
    var retS = "";
    var tempS = "";
    var ss = "";

    if (s.length == 16) {
        tempS = "1110" + s.substring(0, 4);
        tempS += "10" + s.substring(4, 10);
        tempS += "10" + s.substring(10, 16);
        var sss = "0123456789ABCDEF";
        for (var i = 0; i < 3; i++) {
            retS += "%";
            ss = tempS.substring(i * 8, (eval(i) + 1) * 8);
            retS += sss.charAt(Dig2Dec(ss.substring(0, 4)));
            retS += sss.charAt(Dig2Dec(ss.substring(4, 8)));
        }
        return retS;
    }
    return "";
}

　　在js调用ios的时候，如果是中文必须将其编码。此处为编码为utf-8