String.prototype.fill = function(number){var filled ="";for (var i=0;i<number;++i){filled += this;}return filled;} 
String.prototype.padLeft = function(fillc, length) 
        {if (this.length<length){return (fillc.fill(length-this.length)+this).substr(-length);}return this;} 
Number.prototype.padLeft = function(fillc, length) 
    {return this.toString().padLeft(fillc, length);} 
/*string*/ String.prototype.bytesToHexCode=function()  
{ 
    var hexString = ""; 
    for (var i=0; i < this.length; i++)  
    { 
        hexString += this.charCodeAt(i).toString(16).toUpperCase().padLeft("0",2); 
    } 
    return hexString; 
} 

"\u1D538".bytesToHexCode() 
Ergebnis: 1D5338 

/*string*/ String.prototype.toUnicode=function()  
{ 
    var unicodeString = ''; 
    for (var i=0; i < this.length; i++)  
    { 
        var unicode = "\\u" + this.charCodeAt(i).toString(16).toUpperCase().padLeft("0",4); 
        unicodeString += unicode; 
    } 
    return unicodeString; 
} 

"ᵓ8".toUnicode() 
Ergebnis: \u1D53\u0038