• December 2, 2025

My no-fuss code linting and formatting setup

Biome is my absolutely favorite code linter and formatter.

1. Its built with modern JS in mind.
2. It has great default options right out-of-the-box, with just enough configuration.
3. It also formats code, and can replace Prettier.
4. It supports JavaScript and CSS.
5. It has IDE/text editor integrations.
6. It can run in a CI/deployment setup like GitHub Actions.
7. It’s built with Rust and is fast AF!

I’ve been using Biome to build Kelp UI, and it’s been amazing.

Here’s what my biome.json file looks like…

{
	"$schema": "./node_modules/@biomejs/biome/configuration_schema.json",
	"files": {
		"includes": ["src/css/**/*", "src/js/**/*", "tests/**/*.js"]
	},
	"linter": {
		"rules": {
			"suspicious": {
				"noConsole": {
					"level": "warn",
					"options": {
						"allow": ["assert", "error", "info", "warn"]
					}
				}
			}
		}
	},
	"javascript": {
		"formatter": {
			"quoteStyle": "single"
		}
	}
}

This does three things:

1. Tells Biome which directories and files to look at (in this case, my CSS, JS, and test files).
2. Allows console in my code, but only for errors and warnings. If I forget a console.log(), Biome will catch it and yell at me.
3. Switches the JS formatter from double quotes to single quotes (CSS uses double quotes).

Otherwise, the default options are fantastic!

I have two scripts in my package.json file for linting my code:

• lint, which runs npx @biomejs/biome check and logs errors in the console.
• lint:fix, which runs npx @biomejs/biome check --write, an automatically fixes any errors that it can.

I also have an integration in my text editor that shows linting errors and formatting hints live as I write code.

• I use Sublime Text, so I use Sublime LSP with LSP-biome.
• If you use VSCode, Biome has an official extension.

The whole thing is just so nice.

I write code. Biome says, “hey, this looks wrong,” or, “did you mean this?” Then, I can choose a quick fix, ignore it, or figure it out myself.

When I’m ready to deploy, I run npm run lint:fix to lint and format all of my files. And when I push to GitHub, a GitHub Actions script fires off to make sure I didn’t miss anything.

I cannot recommend this setup enough!