add electron support for checking file existance

assets/electron/template/app/src/handlers/fs/exist.js

@@ -0,0 +1,37 @@
+// @ts-check
+
+import { access } from 'node:fs/promises'
+
+/**
+ * @param {import('@pipelab/core').MakeInputOutput<import('@pipelab/core').MessageExistFile, 'input'>} json
+ * @param {import('ws').WebSocket} ws
+ */
+export default async (json, ws) => {
+  try {
+    await access(json.body.path)
+
+    /**
+     * @type {import('@pipelab/core').MakeInputOutput<import('@pipelab/core').MessageExistFile, 'output'>}
+     */
+    const existResult = {
+      correlationId: json.correlationId,
+      url: json.url,
+      body: {
+        success: true
+      }
+    }
+    ws.send(JSON.stringify(existResult))
+  } catch (e) {
+    /**
+     * @type {import('@pipelab/core').MakeInputOutput<import('@pipelab/core').MessageExistFile, 'output'>}
+     */
+    const existResult = {
+      correlationId: json.correlationId,
+      url: json.url,
+      body: {
+        success: false
+      }
+    }
+    ws.send(JSON.stringify(existResult))
+  }
+}

assets/electron/template/app/src/index.js

@@ -21,6 +21,7 @@ import fsReadBinary from './handlers/fs/read-binary.js'
 import fsFolderCreate from './handlers/fs/folder-create.js'
 import fsList from './handlers/fs/list.js'
 import fsFileSize from './handlers/fs/file-size.js'
+import fsExist from './handlers/fs/exist.js'
 
 // window
 import windowMaximize from './handlers/window/maximize.js'
@@ -241,7 +242,8 @@ const createAppServer = (mainWindow, serveStatic = true) => {
             case '/fs/delete':
               throw new Error('Not implemented')
             case '/fs/exist':
-              throw new Error('Not implemented')
+              await fsExist(json, ws)
+              break
             case '/fs/file/append':
               throw new Error('Not implemented')
             case '/fs/list':