Quick start

With @zenfs/core installed, you can start using fs immediately. A single InMemory backend is created by default and mounted on /, so nothing needs to be configured first:

import { fs } from '@zenfs/core'; // You can also use the default export

fs.writeFileSync('/test.txt', 'You can do this anywhere, including browsers!');

const contents = fs.readFileSync('/test.txt', 'utf-8');
console.log(contents);

Persistance

In-memory storage is cleared when the runtime ends. To keep data around, use a backend that persists its data. For example, WebStorage from @zenfs/dom:

import { configureSingle, fs } from '@zenfs/core';
import { WebStorage } from '@zenfs/dom';

await configureSingle({ backend: WebStorage });

if (!fs.existsSync('/test.txt')) {
  fs.writeFileSync('/test.txt', 'This will persist across reloads!');
}

console.log(fs.readFileSync('/test.txt', 'utf-8'));

Using promises

The node:fs/promises API is exposed as promises, and can be imported directly:

import { configureSingle } from '@zenfs/core';
import { exists, writeFile } from '@zenfs/core/promises';
import { IndexedDB } from '@zenfs/dom';

await configureSingle({ backend: IndexedDB });

if (!(await exists('/myfile.txt'))) {
  await writeFile('/myfile.txt', 'Lots of persistent data');
}

You can also import it using the named promises export or by accessing fs.promises.

Next

• Using ZenFS covers mounting multiple backends, the promises API, and mounting at runtime.
• Configuration has many details for configure.
• The playground lets you try backends and configurations without installing anything.