Part of my Java Class file parser

parser.js

function Typedef(bytes) {
    this.bytes = bytes;
};

Typedef.prototype.getData = function(data, start){
  var values = data.slice(start, start + this.bytes);
  var c = 0;
  for(i = 0; i < values.length; i++) {
    var offset = this.bytes - (i + 1);
    c += values[i] * Math.pow(2, offset);
  }
  return c;
};

var uint8 = new Typedef(1);
var uint16 = new Typedef(2);
var uint32 = new Typedef(4);

toHexString = function(bytes) {
    return bytes.toString(16);
};

function readUTF8String(data, start, n) {
    var str = "";

    for (j = 0; j < n; j++) {
        str += String.fromCharCode(uint8.getData(data, start + j));
    }

    return str;
};

var klazz = new klass.Klass();
var p1 = uint8.getData(data, 0);
var p2 = uint8.getData(data, 1);
var p3 = uint8.getData(data, 2);
var p4 = uint8.getData(data, 3);

var maybeCafeBabe = toHexString(p1) + toHexString(p2) + toHexString(p3) + toHexString(p4);

if (maybeCafeBabe == "cafebabe") {
    console.log("java class file");
} else {
    console.log("not a java class file");
}

var minorVersion = uint16.getData(data, 4);
var majorVersion = uint16.getData(data, 6);

console.log("Major: " + majorVersion);
console.log("Minor: " + minorVersion);

var constPoolSize = uint16.getData(data, 8);

console.log("Constant Pool Size: " + constPoolSize);

console.log("First type: " + uint8.getData(data, 10));

console.log("additional: " + uint16.getData(data, 11));

console.log("next byte: " + uint8.getData(data, 13));

console.log("next byte: " + uint16.getData(data, 14));

klazz.name = readUTF8String(data, 16, 11);

console.log("name: " + klazz.name);

console.log("next byte: " + uint8.getData(data, 27));

console.log("next byte: " + uint16.getData(data, 28));