JavaScript / TypeScript are famously free-form, but a number of styles (and style-enforcing tools) have emerged.

“Prettier” is the most recent. It actually parses your code into an AST and then re-prints it according to its style.

“ESLint” is the most widespread; it is more of a framework into which rules can be plugged.

I use “XO”, which is essentially a custom eslint ruleset with a few other nice things tacked on.

The best part of eslint/xo is the “—fix” command, which can auto-fix most mistakes.