Use pure JavaScript to get the color of a pixel on click

imageColor.js

<script type="text/javascript" language="javascript">
  var img = document.getElementById("myImage");

  img.addEventListener("click", function(event) {
      var canvas = document.createElement('canvas');
      canvas.width = img.width;
      canvas.height = img.height;
      canvas.getContext('2d').drawImage(img, 0, 0, img.width, img.height);
      var p = canvas.getContext('2d').getImageData(event.offsetX, event.offsetY, 1, 1).data;
      var hex = "#" + ("000000" + rgbToHex(p[0], p[1], p[2])).slice(-6);
      console.log( hex );            
  });

  function rgbToHex(r, g, b) {
      if (r > 255 || g > 255 || b > 255)
          throw "Invalid color component";
      return ((r << 16) | (g << 8) | b).toString(16);
  }
</script>