add fs.flush() that saves superblock

index.d.ts

@@ -206,6 +206,11 @@ declare module '@isomorphic-git/lightning-fs' {
        * @returns The size of a file or directory in bytes.
        */
       du(filepath: string): Promise<number>
+      /**
+       * Function that saves anything that need to be saved in IndexedBD or custom IDB object. Right now it saves SuperBlock so it's save to dump the object as dump it into a file (e.g. from a Browser)
+       * @returns Promise that resolves when super block is saved to file
+       */
+       flush(): Promise<void>
     }
 
     export interface Options {
@@ -245,8 +250,19 @@ declare module '@isomorphic-git/lightning-fs' {
        * @default false
        */
       defer?: boolean
-
+      db: FS.IDB
+    }
+    export interface IDB {
+      constructor(dbname: string, storename: string): IDB
+      saveSuperblock(sb: Uint8Array): TypeOrPromise<void>
+      loadSuperblock(): TypeOrPromise<FS.SuperBlock>
+      loadFile(inode: number): TypeOrPromise<Uint8Array>
+      writeFile(inode: number, data: Uint8Array): TypeOrPromise<void>
+      wipe(): TypeOrPromise<void>
+      close(): TypeOrPromise<void>
     }
+    type TypeOrPromise<T> = T | Promise<T>
+    export type SuperBlock = Map<string | number, any>
     export interface MKDirOptions {
       /**
        * Posix mode permissions

package.json

@@ -47,6 +47,7 @@
   },
   "files": [
     "**/*.js",
+    "index.d.ts",
     "!__tests__",
     "!coverage"
   ],

src/DefaultBackend.js

@@ -13,7 +13,7 @@ const path = require("./path.js");
 module.exports = class DefaultBackend {
   constructor() {
     this.saveSuperblock = debounce(() => {
-      this._saveSuperblock();
+      this.flush();
     }, 500);
   }
   async init (name, {
@@ -180,4 +180,7 @@ module.exports = class DefaultBackend {
   du(filepath) {
     return this._cache.du(filepath);
   }
+  flush() {
+    return this._saveSuperblock();
+  }
 }

src/PromisifiedFS.js

@@ -198,4 +198,7 @@ module.exports = class PromisifiedFS {
   async du(filepath) {
     return this._backend.du(filepath);
   }
+  async flush() {
+    return this._backend.flush();
+  }
 }

src/index.js

@@ -29,6 +29,7 @@ module.exports = class FS {
     this.symlink = this.symlink.bind(this)
     this.backFile = this.backFile.bind(this)
     this.du = this.du.bind(this)
+    this.flush = this.flush.bind(this)
   }
   init(name, options) {
     return this.promises.init(name, options)
@@ -85,4 +86,8 @@ module.exports = class FS {
     const [resolve, reject] = wrapCallback(cb);
     this.promises.du(filepath).then(resolve).catch(reject);
   }
+  flush(cb) {
+    const [resolve, reject] = wrapCallback(cb);
+    this.promises.flush().then(resolve).catch(reject);
+  }
 }