A puu.sh image searcher

puush.js

function toBase(c, s) {
  var l = c.length,
      _ret = "";
  while (s !== 0) {
    _ret += c[s % l];
    s = Math.floor(s / l);
  }
  return _ret.split("").reverse().join("");
}

function fromBase(c, n) {
  n = n.split("").reverse().join("");
  for (var i = 0, p = n.length, l = c.length, _acc = 0; i < p; ++i) {
    _acc += Math.pow(l, i) * c.indexOf(n[i]);
  }
  return _acc;
}

var c = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'.split("");
var _c = c.length;

function randomId() {
  var s = (~~(Math.random() * 3) + 6).toString(); // Image Ids seem to always start with 7, 8, or 9
  for (var i = 0; i < 4; ++i) {
    s += c[~~(Math.random() * _c)];
  }
  return s;
}

document.body.innerHTML = "";
document.body.style.textAlign = "center";
document.body.style.backgroundColor = "#1b1d1e";
document.body.style.color = "#8f8f8f";
document.body.style.fontFamily = "Helvetica Neue, Helvetica, Neue, Sans, Arial";

var streak = 0;

var idValues = {
  low: 0,
  high: 0,
  initial: randomId()
};

function getPuush(id, reverse) {
  var h1 = document.createElement("h1");
  h1.innerText = id;
  var img = new Image();
  img.onload = function() {
    if (img.width > window.innerWidth * 0.8) {
      img.style.width = "80%";
      img.style.height = "auto";
    }
    document.body.appendChild(h1);
    document.body.appendChild(img);
    streak++;
    setTimeout(function() {
      return getPuush(toBase(c, fromBase(c, id) + (reverse ? -1 : 1)), reverse);
    }, 500);
  };
  img.onerror = function() {
    if (fromBase(c, id) < fromBase(c, idValues.initial)) {
      idValues.low = id;
      h1.innerHTML = id + " &ndash; Image not found! &ndash; continuing search upwards";
      document.body.appendChild(h1);
      return getPuush(toBase(c, fromBase(c, idValues.initial) + 1), false);
    }
    if (idValues.low === 0) {
      h1.innerHTML = "Game over, no images were found";
    } else {
      h1.innerHTML = "Game over, your streak was " + streak + " and contained the range of numbers " + idValues.low + " to " + id;
    }
    document.body.appendChild(h1);
  };
  img.src = "http://puu.sh/" + id + ".jpg";
}

getPuush(idValues.initial, true);