CanvasRenderingContext2D.getContextAttributes()

The CanvasRenderingContext2D.getContextAttributes() method returns an object that contains the actual context parameters. Context attributes can be requested with HTMLCanvasElement.getContext() on context creation.

A CanvasRenderingContext2DSettings object that contains the actual context parameters. It has the following members:

alpha

A Boolean indicating if the canvas contains an alpha channel. If false, the backdrop is always opaque, which can speed up drawing of transparent content and images.

desynchronized

A Boolean indicating the user agent reduced the latency by desynchronizing the canvas paint cycle from the event loop.

Given context attributes were provided on context creation using HTMLCanvasElement.getContext()

let canvas = document.createElement('canvas');
let ctx = canvas.getContext('2d', {alpha: false});

the getContextAttributes() method lets you read back actual attributes used by the user agent:

ctx.getContextAttributes();
// returns {alpha: false, desynchronized: false}

• HTMLCanvasElement.getContext()
• WebGLRenderingContext.getContextAttributes()