Sign extension operators (WebAssembly)Baseline · Widely available
Sign-extension operator instructions extend the width of 8-bit, 16-bit, and 32-bit values to 32-bit and 64-bit values.
Supported in all major browsers for at least 30 months — safe to use without fallbacks. Baseline since Apr 26, 2021. Widely available since Oct 26, 2023.
Browser support
DesktopChrome
1–68Not supported
69+Supportedsince Sep 4, 2018
Current: 155Edge
12–17Not supported
18+Supportedsince Oct 2, 2018
Current: 154Firefox
1–61Not supported
62+Supportedsince Sep 5, 2018
Current: 157Safari
1–14Not supported
14.1+Supportedsince Apr 26, 2021
Current: 27MobileChrome Android
18–68Not supported
69+Supportedsince Sep 4, 2018
Current: 155Firefox Android
4–61Not supported
62+Supportedsince Sep 5, 2018
Current: 157Safari iOS
1–14Not supported
14.5+Supportedsince Apr 26, 2021
Current: 27How 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.