Interface Capabilities

Whether or not the environment allows SharedArrayBuffers to be passed to TextDecoder.decode and TextEncoder.encodeInto directly

• ✅ node
• ✅ deno
• ✅ bun
• ❌ firefox
• ❌ chrome
• ❌ webkit

Whether or not cross-origin checks are enforced for outgoing HTTP requests on this platform.

• ❌ node
• ❌ deno
• ❌ bun
• ✅ firefox
• ✅ chrome
• ✅ webkit

Whether or not the EXTISM_ENABLE_WASI_OUTPUT environment variable has been set.

This value is consulted whenever ExtismPluginOptions#enableWasiOutput is omitted.

Whether or not the host environment has access to a filesystem.

• ✅ node
• ✅ deno
• ✅ bun
• ❌ firefox
• ❌ chrome
• ❌ webkit

Whether or not the host environment supports moving Wasm plugin workloads to a worker. This requires SharedArrayBuffer support, which requires window.crossOriginIsolated to be true in browsers.

See

crossOriginalIsolated on MDN

• ✅ node
• ✅ deno
• ✅ bun
• 🔒 firefox
• 🔒 chrome
• 🔒 webkit

Whether or not ManifestWasm items support the "path:" key.

• ✅ node
• ✅ deno
• ✅ bun
• ❌ firefox
• ❌ chrome
• ❌ webkit

Whether or not the environment supports JSPI.

If supported, host functions may be asynchronous without running the plugin with runInWorker: true.

• ✅ node 23+
• ❌ deno
• ❌ bun
• ❌ firefox
• ❌ chrome
• ❌ webkit

Whether or not the host environment supports timeouts.

• ✅ node
• ✅ deno
• ❌ bun (Exhibits strange behavior when await'ing worker.terminate().)
• ✅ firefox
• ✅ chrome
• ✅ webkit

Whether or not the host environment supports WASI preview 1.

See

WASI and WASI Preview 1

• ✅ node (via node:wasi)
• ✅ deno (via deno.land/std/wasi/snapshot_preview1)
• ❌ bun
• ✅ firefox (via @bjorn3/browser_wasi_shim)
• ✅ chrome (via @bjorn3/browser_wasi_shim)
• ✅ webkit (via @bjorn3/browser_wasi_shim)