JavaScript promise integration (WebAssembly)Baseline · Newly available
The JavaScript promise integration (JSPI) suspends a WebAssembly module when it calls a JavaScript method that returns a promise. The module resumes when the promise is resolved. You can use this to call asynchronous Web APIs from synchronous WebAssembly.
Works in the latest version of every major browser, but older devices may not support it yet. Baseline since Sep 14, 2026.
Browser support
DesktopChrome
1–136Not supported
137+Supportedsince May 27, 2025
Current: 155Edge
12–136Not supported
137+Supportedsince May 29, 2025
Current: 154Firefox
1–152Not supported
153+Supportedsince Jul 21, 2026
Current: 157Safari
1–26.6Not supported
27+Supportedsince Sep 14, 2026
Current: 27MobileChrome Android
18–136Not supported
137+Supportedsince May 27, 2025
Current: 155Firefox Android
4–152Not supported
153+Supportedsince Jul 21, 2026
Current: 157Safari iOS
1–26.6Not supported
27+Supportedsince Sep 14, 2026
Current: 27How to use
Every current browser supports this, but it only became Baseline on Sep 14, 2026. Use it as a progressive enhancement, or keep a fallback if you support older devices.
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.