The shadowColor property
The shadowColor property can be used to set the color of your shadow.
This sets the color of the shadow. The color must be a valid css color (ie gradients and patterns are not permitted here but you can use rgba colors or rgb colors such as: rgba(255,0,0,0.5) rgb(255,0,0) ).
An example
<script>
window.onload = function ()
{
var canvas = document.getElementById("cvs");
var context = canvas.getContext('2d');
var x = 50;
var y = 50;
var width = 100;
var height = 100;
context.shadowColor = 'green';
context.shadowOffsetX = 3;
context.shadowOffsetY = 3;
context.shadowBlur = 15;
context.fillStyle = 'red';
context.fillRect(x, y, width, height);
}
</script>