Linting and formatting

Ende ships a linter and a formatter in the ende binary. No packages to install, no config files required:

ende lint    # catch bugs and anti-patterns
ende fmt     # format code, markdown, and JSON

Both are fast, run the same way locally and in CI, and are configured (when you need to configure anything at all) in the same ende.json as the rest of your project.

Linting

Explore all the lint rules

Linting is the process of analyzing your code for potential errors, bugs, and stylistic issues. Ende's built-in linter, ende lint, supports recommended set of rules from ESLint to provide comprehensive feedback on your code. This includes identifying syntax errors, enforcing coding conventions, and highlighting potential issues that could lead to bugs.

To run the linter, use the following command in your terminal:

ende lint

By default, ende lint analyzes all TypeScript and JavaScript files in the current directory and its subdirectories. If you want to lint specific files or directories, you can pass them as arguments to the command. For example:

ende lint src/

This command will lint all files in the src/ directory.

A finding shows the rule name, the offending code, and a hint:

$ ende lint main.ts
error[require-await]: Async function 'fetchData' has no 'await' expression
 --> /project/main.ts:1:1
  |
1 | async function fetchData() {
  | ^^^^^
  = hint: Remove 'async' keyword from the function or use 'await' expression inside.

  docs: https://docs.ende.sh/lint/rules/require-await

Found 1 problem
Checked 1 file

Some rules can fix the problem for you: run ende lint --fix to apply those fixes automatically. To silence a rule for one line, add an ignore directive naming the rule above it:

// deno-lint-ignore require-await
async function fetchData() {
  return "data";
}

See the ende lint reference for all flags and directive forms.

The linter can be configured in a ende.json file. You can specify custom rules, plugins, and settings to tailor the linting process to your needs.

Linting rules

You can view and search the list of available rules and their usage on the List of rules documentation page.

Formatting

Formatting is the process of automatically adjusting the layout of your code to adhere to a consistent style. Ende's built-in formatter, ende fmt, uses the powerful dprint engine to ensure that your code is always clean, readable, and consistent.

To format your code, simply execute the following command in your terminal:

ende fmt

By default, ende fmt formats all TypeScript and JavaScript files in the current directory and its subdirectories. If you want to format specific files or directories, you can pass them as arguments to the command. For example:

ende fmt src/

This command will format all files in the src/ directory.

Checking your formatting

The ende fmt --check command is used to verify if your code is properly formatted according to Ende's default formatting rules. Instead of modifying the files, it checks them and reports any formatting issues. This is particularly useful for integrating into continuous integration (CI) pipelines or pre-commit hooks to ensure code consistency across your project.

If there are formatting issues, ende fmt --check will list the files that need formatting. If all files are correctly formatted, it will simply exit without any output.

Integration in CI

You can add ende fmt --check to your CI pipeline to automatically check for formatting issues. For example, in a GitHub Actions workflow:

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Install Ende
        run: |
          curl -fsSL https://ende.sh/install.sh | sh
          echo "$HOME/.ende/bin" >> "$GITHUB_PATH"
      - run: ende fmt --check

This ensures that any code changes adhere to the project's formatting standards before being merged.

Configuration

The formatter is configured with the fmt field in your ende.json file. See all formatting options for the full list of settings and their defaults.

ende fmt also reads .editorconfig files and uses them to fill in any option you have not set through a CLI flag or the ende.json fmt block. The precedence is CLI flags, then ende.json, then .editorconfig, then the built-in defaults, so an .editorconfig value only applies when nothing higher up has set it. See Inheriting settings from .editorconfig for the property mappings.