update: fix stout bursts

lib/downloader.js

@@ -1,5 +1,7 @@
 const { spawn } = require('child_process');
 const logger = require('./logger');
+const { from, interval } = require('rxjs');
+const { throttle } = require('rxjs/operators');
 let settings;
 
 try {
@@ -16,8 +18,15 @@ const download = (socket, url) => {
         ['-o', `${settings.download_path || 'downloads/'}%(title)s.%(ext)s`, url]
     )
     ytldp.stdout.on('data', data => {
-        socket.emit('progress', data.toString())
-        logger('download', `Fetching ${data.toString()}`)
+        // reactive programming magic
+        from(Promise.resolve(data))  // stout as promise => Observable
+            .pipe(throttle(() => interval(500)))  // discard events closer than 500ms
+            .subscribe({
+                next: () => {
+                    socket.emit('progress', data.toString()) // finally, emit
+                    logger('download', `Fetching ${data.toString()}`)
+                }
+            })
     })
     ytldp.on('exit', () => {
         socket.emit('progress', 'Done!')