This attribute specifies the color of the shadow. We can define it by the shadowOffsetX, shadowOffsetY, and the shadowBlur property. Here we discuss the shadowBlur Property.
<canvas id="myfirstCanvas" width="250" height="150" style="border:1px solid;#d3d3d3;">
</canvas>
<script type="text/javascript">
var mycanvas=document.getElementById("myfirstCanvas");
var x=mycanvas.getContext("2d");
x.rect(20,30,40,50);
x.fillStyle="pink";
x.shadowColor="black";
x.shadowBlur=20;
x.fill();
</script>
</body>
</html>