coderef

Import and export of mutable globals (WebAssembly)Baseline · Widely available

Mutable global variables are importable and exportable.

Supported in all major browsers for at least 30 months — safe to use without fallbacks. Baseline since Mar 24, 2020. Widely available since Sep 24, 2022.

How to use ↓Compare browsers

Browser support

DesktopChrome
1–73Not supported
74+Supportedsince Apr 23, 2019
Current: 155
Edge
12–18Not supported
79+Supportedsince Jan 15, 2020
Current: 154
Firefox
1–61Not supported
62+Supportedsince Sep 5, 2018
Current: 157
Safari
1–13Not supported
13.1+Supportedsince Mar 24, 2020
Current: 27
MobileChrome Android
18–73Not supported
74+Supportedsince Apr 24, 2019
Current: 155
Firefox Android
4–61Not supported
62+Supportedsince Sep 5, 2018
Current: 157
Safari iOS
1–13Not supported
13.4+Supportedsince Mar 24, 2020
Current: 27

How to use

This feature is Baseline widely available — use it freely, no fallback needed.

Example

Full syntax and examples are on MDN — see the links below.

Feature detection

There’s no simple runtime check for this feature; rely on the support table and test in your target browsers.

Specification

Usage share

Sub-features

Support for each part of the feature (2). The overall table above shows when the whole feature works.

Sub-featureChromeEdgeFirefoxSafariChrome AndroidFirefox AndroidSafari iOS
webassembly.api.Global.Global.mutable69796213.1696213.4
webassembly.definitions.global.mut74796113.1746113.4