OffscreenCanvas.toBlob

The OffscreenCanvas.toBlob() method creates a Blob object representing the image contained in the canvas.

Syntax

Promise<Blob> OffscreenCanvas.toBlob(type, encoderOptions);

Parameters

type Optional

A DOMString indicating the image format. The default type is image/png.

encoderOptions Optional

A Number between 0 and 1 indicating image quality if the requested type is image/jpeg or image/webp. If this argument is anything else, the default value for image quality is used. Other arguments are ignored.

Return value

A Promise returning a Blob object representing the image contained in the canvas.

Examples

var offscreen = new OffscreenCanvas(256, 256);
var gl = offscreen.getContext("webgl");

// ... some drawing using the gl context ...

offscreen.toBlob().then(function(blob) {
  console.log(blob);
});

// Blob { size: 334, type: "image/png" }

Specifications

Currently drafted as a proposal: OffscreenCanvas.

Browser compatibility

[1] This feature is behind a feature preference setting. In about:config, set gfx.offscreencanvas.enabled to true.

See also

• The interface defining this method, OffscreenCanvas.