color converter

gistfile1.txt

<h1>grayscale calculator</h1>

<input type="text" id="input" value="#DA0000" />
<input type="text" id="output" />


<script>     

var inputField = document.getElementById('input');
var outputField = document.getElementById('output');

console.log(input);
inputField.onkeyup = function() {
  inputvalue = input.value.replace(/#/,'');
  val = inputvalue.match(/([\d\w]{2})/g);

  console.log(val);

  var gray = Math.ceil(0.299*parseInt(val[0],16) + 0.587*parseInt(val[1],16) + 0.114*parseInt(val[2],16)); 
  console.log(gray, gray.toString(16));
  output.value=new Array(4).join(gray.toString(16));             
  console.log(output.value);
};

input.onkeyup();
</script>