Formats and validates code files using Prettier and related formatting tools. Supports JavaScript, TypeScript, JSON, CSS, Markdown, and many other file types.
npm install -g prettier) or locally in the project.js, .jsx, .ts, .tsx, .json, .css, .md)npx prettier --version. If missing, install it locally with npm install --save-dev prettier or globally with npm install -g prettier..prettierrc, .prettierrc.json, prettier.config.js, or a "prettier" key in package.json. If no configuration exists, create a .prettierrc with sensible defaults (see ${CLAUDE_SKILL_DIR}/references/implementation.md).npx prettier --check "**/*.{js,jsx,ts,tsx,json,css,md}" --ignore-path .prettierignore to identify files that need formatting. Report the count and list of non-conforming files.npx prettier --write on the target paths. For single files, specify the exact path; for directories, use glob patterns..prettierignore to exclude generated outputs (dist/, build/, *.min.js, *.min.css), dependencies (node_modules/, vendor/), and lock files.husky and lint-staged, then configuring lint-staged in package.json to run prettier --write on staged files matching supported extensions.npx prettier --check to confirm all target files now conform to the configured style rules.A formatting execution report containing:
.prettierrc, .prettierignore)| Error | Cause | Solution |
|---|---|---|
prettier: command not found |
Prettier not installed globally or locally | Run npm install -g prettier or npx prettier --version to use npx |
| Syntax errors in source files | Malformed code that Prettier cannot parse | Fix syntax errors first using npx eslint --fix-dry-run <file> then retry formatting |
| Configuration conflicts | Multiple .prettierrc files or conflicting editorconfig |
Locate all config files with find . -name ".prettier*" and consolidate to a single config |
| Permission denied on write | File or directory lacks write permission | Run chmod u+w <file> to grant write access |
| Parser not found for file type | Unsupported file extension or missing Prettier plugin | Install the appropriate Prettier plugin (e.g., prettier-plugin-svelte) or exclude the file type |
Format a single file:
Trigger: "Format src/app.js"
Process: Run npx prettier --write src/app.js. Report the file as reformatted or already conformant.
Project-wide formatting setup:
Trigger: "Set up code formatting for this project."
Process: Create .prettierrc with project defaults, create .prettierignore excluding build outputs, run npx prettier --write "src/**/*.{js,ts,json,css}", install husky and lint-staged for pre-commit hooks, verify compliance.
Check formatting without modifying files:
Trigger: "Check formatting across the project."
Process: Run npx prettier --check "**/*.{js,jsx,ts,tsx,json,css,md}". Report non-conforming files with their paths. Suggest npx prettier --write to fix.
${CLAUDE_SKILL_DIR}/references/implementation.md -- detailed implementation guide with configuration examples${CLAUDE_SKILL_DIR}/references/errors.md -- common error scenarios and solutions