File watchers are powerful tools. We take them for granted because they’re often baked in, like Webpack rebuilding when you save a file.

Sometimes I’m in an environment without auto-reloading to my disposal. Yesterday, I was working on a CLI tool. The workflow was modify code, save changes, switch to terminal, run the tool, and look at the output. It’s not that bad, but I’d prefer a shorter feedback loop.

This is where a file watcher gives you superpowers. I went with chokidar because it has the friendliest API.

First, install chokidar-cli:

npm i chokidar-cli -g

Then you can watch the files you’re working on, and run a command when they change.

chokidar "src/**/*.php" -c "php ./build.php"

When a PHP file changes in src, the build command will run. If I keep iTerm (and Ray) open alongside my editor, I’ll have immediate feedback for my changes. This is also a great way to automatically run tests for immediate feedback.

chokidar \
"src/**/*.php" "tests/**/*.php" \
-c "phpunit --filter test_i_am_working_on"

I like having a file watcher handy, it’s one of those Swiss Army knife developer tools that came come in useful in many scenarios.