​x
 
<!DOCTYPE html>
<html>
<body>
​
<canvas id="myCanvas" width="300" height="150" style="border:1px solid #d3d3d3;">
Your browser does not support the HTML5 canvas tag.
</canvas>
​
<script>
​
var c=document.getElementById("myCanvas");
var ctx=c.getContext("2d");
ctx.fillStyle="red";
ctx.fillRect(20,20,75,50);
​
//Turn transparency on
ctx.globalAlpha=0.2;
ctx.fillStyle="green"; 
ctx.fillRect(50,50,75,50); 
ctx.fillStyle="blue"; 
ctx.fillRect(80,80,75,50);
</script>
​
</body>
</html>
​