Joomla 4 uses ES6 syntax where possible. As part of this change we decided to use an industry standard codestyle rules for our JavaScript - the AirBNB coding standards. These can be found on their GitHub page.

We have four modifications to the defaults:

1. We allow parameter reassignment of function parameters to allow easier setting of defaults (for examples please see the ESLint rules here)

2. We only allow the imports of dependencies from NPM in our build directory (build/) (rather than in all files)

3. We currently allow browser alerts using the alert() function (the long term intention is to disable this as we move to our custom element alerts)

4. We always enable JavaScript strict mode as we aren't using JavaScript modules at this time

We also use ESLint to enforce these rules. If you are familiar with JavaScript from other projects you've worked on you can find our ESLint rules on GitHub