OffscreenCanvas.toBlob()

This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for the proper prefixes to use in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the spec changes.

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.

Feature	Chrome	Firefox (Gecko)	Internet Explorer	Opera	Safari
Basic support	Not supported	46 (46) [1]	Not supported	Not supported	Not supported

Feature	Android	Firefox Mobile (Gecko)	IE Mobile	Opera Mobile	Safari Mobile
Basic support	Not supported	46.0 (46) [1]	Not supported	Not supported	Not supported

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

OffscreenCanvas.toBlob()

Syntax

Parameters

Return value

Examples

Specifications

Browser compatibility

See also

Document Tags and Contributors