You either created a project for a new app or got the sources of an existing app. This is how you do everyday development now:
Like on most Node.js projects, you need to install the dependencies once at the
beginning with npm ci and only need to repeat that later if the dependencies
change.
During active development we recommend to run npm run watch: It compiles and
packs all your code into dist/bundle.js as well as continuously checking the
types. It then waits, watches your code and whenever you save source files it
creates a new dist/bundle.js (Ctrl+C to stop).
If you just want to compile and pack the code only once, you can use
npm run build:dev instead. There is also npm run build:prod which too
creates a dist/bundle.js once, but contrary to watch and build:dev it is
optimized for production use (e.g. the bundle is minified).
Start nRF Connect for Desktop. It will find all apps in
~/.nrfconnect-apps/local and through the package.json in your project pick
up the dist/bundle.js that was build before. Because of this, it display the
app it in the list of all apps with a “local” underneath it and you can launch
it from there.
When you edit the source of the app and it is recompiled (probably by keeping
npm run watch running), pressing Ctrl+R (Windows or Linux) or Cmd+R
(macOS) in the running app window will make it reload.
Chrome Developer Tools can be opened by pressing Ctrl+Alt+I (Windows/Linux) or
Cmd+Option+I (macOS). We recommend that you
install the DevTools for React and Redux.
You can run the static checks (like linting and type checking) with
npm run check and the unit tests with npm test.
When you want to give your development version of an app to others, run
npm pack. This will create a file like pc-nrfconnect-boilerplate-0.0.1.tgz,
which you can send to others, who are supposed to test your app. Then they can
install that app locally.