<!DOCTYPE html>
<html>
<body>
<canvas id ="output" width="100" height="100" style="background: blue;"></canvas>
<script>
var canvas = document.getElementById('output');
var ctx = canvas.getContext('2d');

ctx.fillStyle = 'green';
ctx.roundRect(10, 10, 80, 80, [20, 40, 10]);
ctx.fill();
</script>
</body>
</html>
