<!DOCTYPE html>
<html>
<body>
<canvas id ="output" width="200" height="100"></canvas>
<script>
var canvas = document.getElementById('output');
var ctx = canvas.getContext('2d');

var linearGradient = ctx.createLinearGradient(0, 0, 100, 100);
linearGradient.addColorStop(0, 'blue');
linearGradient.addColorStop(0.5, 'red');
linearGradient.addColorStop(1, 'white');
ctx.fillStyle = linearGradient;
ctx.fillRect(0, 0, 100, 100);

var radialGradient = ctx.createRadialGradient(150, 50, 0, 150, 50, 50);
radialGradient.addColorStop(0, 'blue');
radialGradient.addColorStop(0.5, 'red');
radialGradient.addColorStop(1, 'white');
ctx.fillStyle = radialGradient;
ctx.fillRect(100, 0, 100, 100);
</script>
</body>
</html>