Web/API/OffscreenCanvas/convertToBlob

This is an experimental technologyCheck the Browser compatibility table carefully before using this in production.

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

Syntax

Promise<Blob> OffscreenCanvas.convertToBlob(options);

Parameters

optionsOptional

You can specify several options when converting your OffscreenCanvas object into a Blob object, for example:

const blob = offscreenCanvas.convertToBlob({
  type: "image/jpeg",
  quality: 0.95
});

options:

type: A DOMString indicating the image format. The default type is image/png.
quality: A Number between 0 and 1 indicating image quality if the type option 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.convertToBlob().then(function(blob) {
  console.log(blob);
});

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

Specifications

Specification	Status	Comment
HTML Living StandardThe definition of 'OffscreenCanvas: convertToBlob' in that specification.	Living Standard

Browser compatibility

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-dataand send us a pull request.

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`convertToBlob` Experimental'	Chrome Full support 69	Edge Full support ≤79	Firefox Partial support 46 Notes' Alternate Name' Disabled' Partial support 46 Notes' Alternate Name' Disabled' Notes' See bug 1390089. Alternate Name' Uses the non-standard name: `toBlob` Disabled' From version 46: this feature is behind the `gfx.offscreencanvas.enabled` preference. To change preferences in Firefox, visit about:config.	IE No support No	Opera Full support 56	Safari No support No	WebView Android No support No	Chrome Android Full support 69	Firefox Android Partial support 46 Notes' Alternate Name' Disabled' Partial support 46 Notes' Alternate Name' Disabled' Notes' See bug 1390089. Alternate Name' Uses the non-standard name: `toBlob` Disabled' From version 46: this feature is behind the `gfx.offscreencanvas.enabled` preference. To change preferences in Firefox, visit about:config.	Opera Android Full support 48	Safari iOS No support No	Samsung Internet Android Full support 10.0

Legend

Full support: Full support
Partial support: Partial support
No support: No support
Experimental. Expect behavior to change in the future.': Experimental. Expect behavior to change in the future.
See implementation notes.': See implementation notes.
User must explicitly enable this feature.': User must explicitly enable this feature.
Uses a non-standard name.': Uses a non-standard name.