node.js watch the folder and run script

Question

I newb in node.js In my project I use PM2 to restart node.js and it works fine.

But, I need to watch folder for changes, start script and not restart it after exit.

For simplicity I use yml for I18n. My goal, when I make changes in yml file, run script to convert it to json and that's all. Wait until new changes in yml file.

PM2 works, but it tries restart script again and again after each exit.

PM2 | App [i18n compile] with id [1] and pid [28803], exited with code [0] via signal [SIGINT] PM2 | Script /home/.../src/i18n/convert.js had too many unstable restarts (16). Stopped. "errored"

May be I should use another tool for this issue?

Answer 1

nodemon is a tool that will allow you to make a change to a file in a directory and automatically run a script

nodemon can be installed by npm install -g nodemon

executing nodemon script.js will automatically run node script.js when there is either a change to script.js or to any other file within the same directory as script.js

Answer 2

I reminded to myself that live in async environment:

1. Wrote own watcher.
2. Added locales dir to PM2 ignore_watch in main app.
3. Added my watcher as PM2 app, but watching only to watcher.

---

{
  name         : 'I18n compiler',
  interpreter  : 'babel-node',
  script       : 'tools/locales.watcher.js',
  cwd          : path.root,
  watch        : 'tools/locales.watcher.js',
  ignore_watch : ['config', 'src', 'server', 'package.json'],
  env: {
    NODE_PATH: path.src,
    NODE_ENV: 'development'
  },
}

---

import fs      from 'fs';
import config  from '../config/general';
import convert from 'i18n/convert.js';

const { path } = config;

 // Synchronous recursively list files in a directory
function getFilesRecur(dir, filelist) {
  const files = fs.readdirSync(dir);
  filelist = filelist || [];
  files.forEach(function(file) {
    if (fs.statSync(path.join(dir, file)).isDirectory()) {
      filelist = getFilesRecur(path.join(dir, file), filelist);
    } else if ((/\.(yml|yaml)$/i).test(file)) {
      filelist.push(path.join(dir, file));
    }
  });
  return filelist;
}

export default function setupLocalesWatcher(){
  const files = getFilesRecur(path.i18n);

  files.forEach(function(file) {
    console.log(`Watching: ${file}`);
    fs.watchFile(file, () => {
      convert(file);
    });
  });

}

Answer 3

Node now has a --watch flag (experimental at moment)

node --watch index.js

you can read more about it and its options in the docs here:

https://nodejs.org/docs/latest/api/cli.html#--watch