The filesystem for Wasm!


import { WasmFs } from "@wasmer/wasmfs".


new WasmFs(): WasmFs

Constructor that returns a WasmFs instance.

Please see the section below on instance properties to see a list of the properties on the returned instance

Instance Properties


wasmFs.fs: MemFs

​memfs' node fs implementation object. See the node fs documentation for API usage.

NOTE: The functions on this fs implementation can easily be over-ridden to provide custom functionality when your Wasm module (running with @wasmer/wasi) tries to do file system operations

const wasmFs = new WasmFs();
const originalWriteFileSync = wasmFs.fs.writeFileSync;
wasmFs.fs.writeFileSync = (path, text) => {
console.log("File written:", path);
originalWriteFileSync(path, text);
wasmFs.fs.writeFileSync("/dev/stdout", "Quick Start!");
// Would log: "File written: /dev/stdout"


wasmFs.getStdOut(): string

Returns the current standard output (/dev/stdout) of the filesystem.