docs: ✏️ add FSA readme

Author: streamich

README.md

@@ -1,9 +1,7 @@
 # memfs
 
-[![][chat-badge]][chat] [![][npm-badge]][npm-url]
+[![][npm-badge]][npm-url]
 
-[chat]: https://onp4.com/@vadim/~memfs
-[chat-badge]: https://img.shields.io/badge/Chat-%F0%9F%92%AC-green?style=flat&logo=chat&link=https://onp4.com/@vadim/~memfs
 [npm-url]: https://www.npmjs.com/package/memfs
 [npm-badge]: https://img.shields.io/npm/v/memfs.svg
 
@@ -19,8 +17,9 @@ npm i memfs
 
 - Documentation
   - [In-memory Node.js `fs` API](./docs/node/index.md)
-  - `experimental` [`fs` to File System Access API adapter](./docs/fsa/fs-to-fsa.md)
-  - `experimental` [File System Access API to `fs` adapter](./docs/fsa/fsa-to-fs.md)
+  - [In-memory browser FSA (File System Access) API](./docs/fsa/fsa.md)
+  - [`fs` to File System Access API adapter](./docs/fsa/fs-to-fsa.md)
+  - [File System Access API to `fs` adapter](./docs/fsa/fsa-to-fs.md)
   - `experimental` [`crudfs` a CRUD-like file system abstraction](./docs/crudfs/index.md)
   - `experimental` [`casfs` Content Addressable Storage file system abstraction](./docs/casfs/index.md)
   - [Directory `snapshot` utility](./docs/snapshot/index.md)

docs/fsa/fsa.md

@@ -0,0 +1,43 @@
+# In-memory File System Access (FSA) API implementation
+
+In-memory file-system with browser FSA API. Construct a new instance:
+
+
+## Quick Start
+
+Create a new instance of FSA filesystem:
+
+```ts
+import {fsa} from 'memfs/lib/fsa';
+
+// Create a new filesystem.
+const {dir, core} = fsa({ mode: 'readwrite' });
+
+// Create a folder and a file.
+const dir2 = await dir.getDirectoryHandle('new-folder', { create: true });
+const file = await dir2.getFileHandle('file.txt', { create: true });
+await (await file.createWritable()).write('Hello, world!');
+
+// Export whole filesystem to JSON.
+console.log(core.toJSON());
+// { '/new-folder/file.txt': 'Hello, world!' }
+```
+
+Create a new FSA filesystem from JSON:
+
+```ts
+const {dir, core} = fsa({ mode: 'readwrite' });
+
+// Import JSON.
+core.fromJSON({
+  'documents/readme.txt': 'Welcome!',
+  'photos/vacation.jpg': Buffer.from('fake-jpg-data'),
+  'empty-folder': null,
+}, '/');
+
+// Use FSA API.
+const dir2 = await dir.getDirectoryHandle('documents');
+const file = await dir2.getFileHandle('readme.txt');
+const fileContent = await file.getFile();
+console.log(await fileContent.text()); // 'Welcome!'
+```

docs/node/index.md

@@ -17,8 +17,6 @@ In-memory file-system with [Node's `fs` API](https://nodejs.org/api/fs.html).
 - [Relative paths](./relative-paths.md)
 - [Dependencies](./dependencies.md)
 
-[chat]: https://onp4.com/@vadim/~memfs
-[chat-badge]: https://img.shields.io/badge/Chat-%F0%9F%92%AC-green?style=flat&logo=chat&link=https://onp4.com/@vadim/~memfs
 [npm-url]: https://www.npmjs.com/package/memfs
 [npm-badge]: https://img.shields.io/npm/v/memfs.svg
 [travis-url]: https://travis-ci.org/streamich/memfs