GPUBuffer: mapAsync() method

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

See full compatibility

Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

Note: This feature is available in Web Workers.

The mapAsync() method of the GPUBuffer interface maps the specified range of the GPUBuffer. It returns a Promise that resolves when the GPUBuffer's content is ready to be accessed. While the GPUBuffer is mapped it cannot be used in any GPU commands.

Once the buffer is successfully mapped (which can be checked via GPUBuffer.mapState), calls to GPUBuffer.getMappedRange() will return an ArrayBuffer containing the GPUBuffer's current values, to be read and updated by JavaScript as required.

When you have finished working with the GPUBuffer values, call GPUBuffer.unmap() to unmap it, making it accessible to the GPU again.

Syntax

mapAsync(mode)
mapAsync(mode, offset, size)

Parameters

mode

A bitwise flag that specifies whether the GPUBuffer is mapped for reading or writing. Possible values are:

GPUMapMode.READ

The GPUBuffer is mapped for reading. Values can be read, but any changes made to the ArrayBuffer returned by GPUBuffer.getMappedRange() will be discarded once GPUBuffer.unmap() is called.

Read-mode mapping can only be used on GPUBuffers that have a usage of GPUBufferUsage.MAP_READ set on them (i.e., when created with GPUDevice.createBuffer()).

GPUMapMode.WRITE

The GPUBuffer is mapped for writing. Values can be read and updated — any changes made to the ArrayBuffer returned by GPUBuffer.getMappedRange() will be saved to the GPUBuffer once GPUBuffer.unmap() is called.

Write-mode mapping can only be used on GPUBuffers that have a usage of GPUBufferUsage.MAP_WRITE set on them (i.e., when created with GPUDevice.createBuffer()).

offset Optional

A number representing the offset, in bytes, from the start of the buffer to the start of the range to be mapped. If offset is omitted, it defaults to 0.

size Optional

A number representing the size, in bytes, of the range to be mapped. If size is omitted, the range mapped extends to the end of the GPUBuffer.

Return value

A Promise that resolves to Undefined when the GPUBuffer's content is ready to be accessed.

Validation

The following criteria must be met when calling mapAsync(), otherwise an OperationError DOMException is thrown, the promise is rejected, and a GPUValidationError is generated:

offset is a multiple of 8.
The total range to be mapped (size if specified, or GPUBuffer.size - offset if not) is a multiple of 4.
The total range to be mapped is inside the bounds of the GPUBuffer.
If mode is GPUMapMode.READ, the GPUBuffer has a usage of GPUBufferUsage.MAP_READ.
If mode is GPUMapMode.WRITE, the GPUBuffer has a usage of GPUBufferUsage.MAP_WRITE.

Examples

See the main GPUBuffer page for an example.

Specifications

Specification
WebGPU # dom-gpubuffer-mapasync

Browser compatibility

	desktop					mobile							server
	Chrome	Edge	Firefox	Opera	Safari	Chrome Android	Firefox for Android	Opera Android	Safari on iOS	Samsung Internet	WebView Android	WebView on iOS	Deno
`mapAsync`	Chrome – Partial support Chrome 113 (Release date: 2023-05-02) footnote Partial support footnote Supported on ChromeOS, macOS, and Windows. footnote Supported on Linux (Intel Gen12+ GPUs only) since Chrome 144.	Edge – Partial support Edge 113 (Release date: 2023-05-05) footnote Partial support footnote Supported on ChromeOS, macOS, and Windows. footnote Supported on Linux (Intel Gen12+ GPUs only) since Edge 144.	Firefox – Partial support Firefox 141 (Release date: 2025-07-22) footnote Partial support footnote Supports all contexts except service workers. See bug 1942431. footnote Supports Windows since Firefox 141. See bug 1972486. footnote Supports macOS Tahoe on Apple silicon since Firefox 145. See bug 1992212. footnote Supports older macOS versions on Apple silicon since Firefox 147. See bug 1993341. footnote Does not support macOS on Intel CPUs. See bug 2004105. footnote Does not support Linux. See bug 2006676.	Opera – Partial support Opera 99 (Release date: 2023-05-16) footnote Partial support footnote Supported on ChromeOS, macOS, and Windows. footnote Supported on Linux (Intel Gen12+ GPUs only) since Opera 128.	Safari – Full support Safari 26 (Release date: 2025-09-15) footnote Full support	Chrome Android – Full support Chrome Android 121 (Release date: 2024-01-23) footnote Full support	Firefox for Android – No support Firefox for Android footnote No support	Opera Android – Full support Opera Android 81 (Release date: 2024-03-14) footnote Full support	Safari on iOS – Full support Safari on iOS 26 (Release date: 2025-09-15) footnote Full support	Samsung Internet – Full support Samsung Internet 25 (Release date: 2024-04-24) footnote Full support	WebView Android – Full support WebView Android 121 (Release date: 2024-01-23) footnote Full support	WebView on iOS – Full support WebView on iOS 26 (Release date: 2025-09-15) footnote Full support	Deno – No support Deno 1.8 – 1.31 (Release date: 2021-03-02) footnote Removed in 1.32 and later Deno – No support Deno 1.39 (Release date: 2023-12-14) disabled disabled From version 1.39 users must explicitly set the `--unstable-webgpu` runtime flag.

Tip: you can click/tap on a cell for more information.

Full support: Full support
Partial support: Partial support
No support: No support
: User must explicitly enable this feature.
: Has more compatibility info.

GPUBuffer: mapAsync() method

Legend