hello.. im new in javascript.. just started learning actually.. i know the basics and i have a question..

why doesnt this work?

Code:
<!DOCTYPE html>
<html>
<body>

<h1>My First JavaScript</h1>

<p id="demo" style="color:#000000;">
JavaScript can change the style of an HTML element.
</p>

<script>
function myFunction()
{
x=document.getElementById('demo') // Find the element
if (x.style.match("ff"))
  {
     x.style="color:#000000";
  }
else
  {
     x.style="color:#ff0000";          // Change the style
  }
}
</script>
<button type="button" onclick="myFunction()">Click Me!</button>

</body>
</html>