node.js检查是否已将新文件复制到磁盘

Question

I'm trying to write a tethered shooting app with electron / node.js.

The communication between camera and computer is managed by the software, which ships with the camera. The new pictures are directly copied to my local hard disk. After that my app should show the new picture as fast as possible.

I set up a chokidar watcher for the directory where my new pictures arrive. Unfortunately the

awaitWriteFinish: {stabilityThreshold: 500, pollInterval: 50}

option of chokidar acts very slowly and sometimes triggers the add-event too early.

My idea to circumvent this was to write my own polling mechanism after the watcher (without awaitWriteFinish option) triggers an event.

I tried fs.stats for polling but fs.stats doesn't recognize the current file size but the total file size.

Is there a easy node.js / javascript / jquery approach to detect if the new file is completely written to disk?

Any help apprechiated.

Answer 1

I would use manual approach like this.

fs.writeSync()

notifyWhateverEnpoint('writing is finished!') // depending on your app, you should choose how to notify it about finishing

Answer 2

I believe you could watch the directory for changes. Perhaps scan it first to have a list of files. For example if file you are on Windows and file is saved on C:\\temp

 const fs = require('fs') const saveDir = 'C\\\\temp' let currentFiles = []; // Read all cuurent files in directory fs.readdirSync(saveDir, (error, files) => { currentFiles = files; }); fs.watch(saveDir, (eventType, fileName) => { if (currentFiles.includes(fileName)) { return; } // Handle rename event // Handle change event }); 

More info here:

https://nodejs.org/api/fs.html#fs_fs_watch_filename_options_listener