Running task on file change in npm scripts

[Suiseki]

Hi,
I would like to make a task, that is launched while one of the files in watched directory changes.
I am using npm scripts
"scripts": { "app01": "node alerts/changes.js", "watch": "watch ./js/*.js npm run app01" },
and running it in command line:
npm run watch
but it ends with error: ERR! Failed at the try02@1.0.2 watch script 'watch ./js/*.js npm run app01'. What is the proper syntax?

[jcollum]

In my package.json:

"watch": "watch 'npm run debug-no-inspect' ./src -d",

then run it with npm run watch

For you you'd want to make a different entry in package.json:

"alert-change": "node alerts/changes.js"

And then put that in the single quotes above.

But you may be better off just spawning a file watcher node process by itself.

[Suiseki]

Thank you for the answer. I still have a problem. I can't run commands within single quotes. Is it matter of operation system (Windows 10). I am also not sure what command is in syntax:
watch <command> [...directory] [OPTIONS]
is it a name of my other custom script in package.json file as i.e. build:js, sometest od myaction could be? Or there is some fixed set of commands i can only use like build, install, help?
Following your example I made mine:
"watch": "watch npm run myfile ./js",
but i get an error, that there is no file rike 'run' in my directory.

[jcollum]

Try escaping the quotes? This might be better off on StackOverflow...

[levithomason]

Windows requires the use of double quotes (not a watch thing, it's a windows thing). You'll need to escape them as well so they aren't ending the JSON value early:

{
  "scripts": {
    "watch": "watch \"npm run myfile\" ./js",
  }
}