The CanvasRenderingContext2D.fillRect() method of the Canvas 2D API draws a rectangle that is filled according to the current fillStyle.

This method draws directly to the canvas without modifying the current path, so any subsequent fill() or stroke() calls will have no effect on it.

fillRect(x, y, width, height)

The fillRect() method draws a filled rectangle whose starting point is at (x, y) and whose size is specified by width and height. The fill style is determined by the current fillStyle attribute.

x

The x-axis coordinate of the rectangle's starting point.

y

The y-axis coordinate of the rectangle's starting point.

width

The rectangle's width. Positive values are to the right, and negative to the left.

height

The rectangle's height. Positive values are down, and negative are up.

None (undefined).

This example draws a filled green rectangle using the fillRect() method.

HTML

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

JavaScript

The rectangle's top-left corner is at (20, 10). It has a width of 150 and a height of 100.

const canvas = document.getElementById("canvas");
const ctx = canvas.getContext("2d");
ctx.fillStyle = "green";
ctx.fillRect(20, 10, 150, 100);

Result

This code snippet fills the entire canvas with a rectangle. This is often useful for creating a background, on top of which other things may then be drawn. To achieve this, the dimensions of the rectangle are set to equal the <canvas> element's width and height attributes.

const canvas = document.getElementById("canvas");
const ctx = canvas.getContext("2d");
ctx.fillRect(0, 0, canvas.width, canvas.height);

• The interface defining this method: CanvasRenderingContext2D
• CanvasRenderingContext2D.fillStyle
• CanvasRenderingContext2D.clearRect()
• CanvasRenderingContext2D.strokeRect()