<canvas id="myCanvas" width="200" height="100" style="border:1px solid #d3d3d3;">

var c = document.getElementById('myCanvas');

var ctx = c.getContext('2d');

var gra = ctx.createRadialGradient(40,50,20,40,60,100);

gra.addColorStop(0,'red');

gra.addColorStop(1,'green');

ctx.fillStyle = gra;

ctx.fillRect(10,10,180,90)