The CanvasRenderingContext2D.shadowOffsetY property of the Canvas 2D API specifies the distance that shadows will be offset vertically.

A float specifying the distance that shadows will be offset vertically. Positive values are down, and negative are up. The default value is 0 (no vertical offset). Infinity and NaN values are ignored.

This example adds a blurred shadow to a rectangle. The shadowColor property sets its color, shadowOffsetY sets its offset 25 units towards the bottom, and shadowBlur gives it a blur level of 10.

HTML

<canvas id="canvas"></canvas>

JavaScript

const canvas = document.getElementById("canvas");
const ctx = canvas.getContext("2d");

// Shadow
ctx.shadowColor = "red";
ctx.shadowOffsetY = 25;
ctx.shadowBlur = 10;

// Rectangle
ctx.fillStyle = "blue";
ctx.fillRect(20, 20, 150, 80);

Result

• The interface defining this property: CanvasRenderingContext2D
• CanvasRenderingContext2D.shadowOffsetX
• CanvasRenderingContext2D.shadowColor
• CanvasRenderingContext2D.shadowBlur