<!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");
var grd = ctx.createLinearGradient(0, 0, 170, 0);
grd.addColorStop(0, "black");
grd.addColorStop(1, "white");
ctx.fillStyle = grd;
ctx.fillRect(20, 20, 150, 100);
</script>
</body>
</html>