Random squares

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/jscolor/2.0.4/jscolor.js"></script>
<p>
  Beads in row:
  <input type="number" id="inputCols" min="2" max="60" value="12">
</p>
<p>
  Gradient rows count:
  <input type="number" id="inputRows" min="2" max="60" value="12">
</p>
<p>
  First bead color:
  <input class="jscolor" value="FF44CC" id="firstColor">
</p>
<p>
  Second bead color:
  <input class="jscolor" value="00FFAA" id="secondColor">
</p>
<p>
  Render type:
</p>
<span>
<input id="Radio1" name="algorithm" type="radio" value="random" checked="checked">
<label for="Radio1">Random</label>
</span>

<span>
<input id="Radio2" name="algorithm" type="radio" value="regular" >
<label for="Radio2">Regular</label>
</span>

<span>
<input id="Radio3" name="algorithm" type="radio" value="dither" >
<label for="Radio3">Dither</label>
</span>
<p>
  <button onclick="run()">Render!</button>
  <br>
  <br>
</p>

CSS

.cell {
  float: left;
  font-size: 10px;
}

.cell::before {
  counter-increment: section;
  /* Increment the value of section counter by 1 */
  content: counter(section);
  /* Display the value of section counter */
}

.container {
  border: 0px solid #000;
  counter-reset: section;
}

button {
  margin-left: 0;
}

input,
button {
  font-size: 1em;
  width: 4.5em;
  padding: 3px;
  margin: 2px 0px;
  border: 1px solid #ddd;
  border-radius: 5px;
  text-align: center;
}

input[type=number] {
  width: 2.5em;
}

input:focus {
  outline: none;
}

span {
  /* style this span element so we can display nicely, this stlying is not neccessary */
  margin: 10px 0;
  display: block;
  width: 100%;
  float: left;
}

input[type="radio"],
input[type="checkbox"] {
  /* hide the inputs */
  opacity: 0;
}


/* style your lables/button */

input[type="radio"] + label,
input[type="checkbox"] + label {
  /* keep pointer so that you get the little hand showing when you are on a button */
  cursor: pointer;
  /* the following are the styles */
  padding: 4px 10px;
  border: 1px solid #ccc;
  background: #efefef;
  color: #aaa;
  border-radius: 3px;
  text-shadow: 1px 1px 0 rgba(0, 0, 0, 0);
}

input[type="radio"]:checked + label,
input[type="checkbox"]:checked + label {
  /* style for the checked/selected state */
  background: #777;
  border: 1px solid #444;
  text-shadow: 1px 1px 0 rgba(0, 0, 0, 0.4);
  color: white;
}

JavaScript

function run() {
  var o = document.getElementById("randomBlock");
  if (o) {
    o.parentNode.removeChild(o);
  }
  var rows = parseInt(document.getElementById('inputRows').value);
  var cols = parseInt(document.getElementById('inputCols').value);
  var algorithm = document.querySelector('input[name="algorithm"]:checked').value;
  var size = 20;

  var container = document.createElement("div");
  container.id = "randomBlock";
  container.className = "container";
  container.style.width = (cols * size) + "px";
  container.style.height = (rows * size) + "px";

  if (algorithm == 'dither') {
    var colors = dither(rows, cols);
    for (var row = 0; row < rows; row++) {
      for (var col = 0; col < cols; col++) {
        o = document.createElement("div");
        o.className = "cell";
        o.style.height = size + "px";
        o.style.width = size + "px";
        o.style.backgroundColor = colors[row][col];
        container.appendChild(o);
      }
    }
  }
  if (algorithm == 'regular') {
    for (var row = 0; row < rows; row++) {
      var bucket = createBucket(row, rows, cols);
      for (var col = 0; col < cols; col++) {
        o = document.createElement("div");
        o.className = "cell";
        o.style.height = size + "px";
        o.style.width = size + "px";
        o.style.backgroundColor = chooseColor(bucket, col);
        container.appendChild(o);
      }
    }
  }
  if (algorithm == 'random') {
    for (var row = 0; row < rows; row++) {
      var bucket = createRandomBucket(row, rows, cols);
      for (var col = 0; col < cols; col++) {
        o = document.createElement("div");
        o.className = "cell";
        o.style.height = size + "px";
        o.style.width = size + "px";
        o.style.backgroundColor = chooseColor(bucket, col);
        container.appendChild(o);
      }
    }
  }
  document.body.appendChild(container);
}

function createBucket(row, rows, cols) {
  var colorPercent = transform(row, rows);
  colPercent = 100 / cols;
 ...