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# prettier-eslint-cli
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prettier-eslint-cli is a command-line interface for formatting JavaScript files using both Prettier and ESLint. It combines Prettier's formatting capabilities with ESLint's linting rules, allowing developers to maintain consistent code style while respecting project-specific ESLint configurations.
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## Package Information
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- **Package Name**: prettier-eslint-cli
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- **Package Type**: npm
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- **Language**: JavaScript (Node.js)
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- **Installation**: `npm install --save-dev prettier-eslint-cli`
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## Core Imports
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This package provides a CLI binary rather than importable modules:
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```bash
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# Global installation
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npm install -g prettier-eslint-cli
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prettier-eslint "src/**/*.js"
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# Local installation (recommended)
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npm install --save-dev prettier-eslint-cli
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npx prettier-eslint "src/**/*.js"
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```
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## Basic Usage
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```bash
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# Format files matching a glob pattern
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prettier-eslint "src/**/*.js"
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# Format files and write changes in-place
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prettier-eslint --write "src/**/*.js"
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# Format code from stdin
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echo "const   foo =   'bar'" | prettier-eslint --stdin
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# Check for formatting differences (useful in CI)
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prettier-eslint --list-different "src/**/*.js"
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```
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In package.json scripts:
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```json
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{
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  "scripts": {
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    "format": "prettier-eslint --write \"src/**/*.js\"",
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    "format:check": "prettier-eslint --list-different \"src/**/*.js\""
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  }
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}
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```
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## Architecture
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prettier-eslint-cli operates as a file processing pipeline:
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1. **File Discovery**: Uses glob patterns to find target files
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2. **Ignore File Processing**: Applies .eslintignore and .prettierignore rules
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3. **Format Engine**: Delegates to prettier-eslint for actual formatting
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4. **Output Processing**: Handles writing files, stdout output, or diff reporting
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5. **Error Handling**: Provides comprehensive error reporting and debugging information
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The tool can process files from glob patterns or stdin, with extensive configuration options for both Prettier and ESLint behavior.
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## Capabilities
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### File Pattern Processing
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Process multiple files using glob patterns with support for ignore files and custom patterns.
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```bash { .api }
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prettier-eslint <globs>... [options]
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# Examples:
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prettier-eslint "src/**/*.js"
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prettier-eslint "lib/**/*.js" "test/**/*.js"
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prettier-eslint "**/*.{js,jsx,ts,tsx}"
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```
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**Glob Pattern Options:**
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- Multiple glob patterns are supported
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- Automatically excludes `**/node_modules/**` unless explicitly included
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- Supports standard glob syntax (*, **, ?, [], {})
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### Output Mode Control
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Control how formatted results are output - to stdout, written in-place, or as difference reports.
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```bash { .api }
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# Write formatted content to stdout (default)
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prettier-eslint "src/**/*.js"
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# Write changes in-place to original files
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prettier-eslint --write "src/**/*.js"
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# List files that would be changed (CI mode)
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prettier-eslint --list-different "src/**/*.js"
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```
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### Stdin Processing
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Process code from standard input for integration with editors and pipes.
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```bash { .api }
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# Format code from stdin
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echo "const   foo = 'bar'" | prettier-eslint --stdin
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# Specify file path for stdin (affects ESLint config detection)
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echo "const   foo = 'bar'" | prettier-eslint --stdin --stdin-filepath src/example.js
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```
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### Ignore File Configuration
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Control which files are processed using ignore file patterns.
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```bash { .api }
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# Apply .eslintignore patterns (default: true)
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prettier-eslint --eslint-ignore "src/**/*.js"
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# Disable .eslintignore patterns
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prettier-eslint --no-eslint-ignore "src/**/*.js"
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# Apply .prettierignore patterns (default: true)
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prettier-eslint --prettier-ignore "src/**/*.js"
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# Disable .prettierignore patterns
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prettier-eslint --no-prettier-ignore "src/**/*.js"
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# Include dotfiles in processing
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prettier-eslint --include-dot-files "src/**/*"
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# Add custom ignore patterns
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prettier-eslint --ignore "**/*.min.js" --ignore "dist/**" "src/**/*.js"
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```
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### Tool Configuration
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Configure paths to eslint and prettier binaries and configuration files.
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```bash { .api }
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# Specify eslint binary path
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prettier-eslint --eslint-path ./node_modules/.bin/eslint "src/**/*.js"
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# Specify eslint config file
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prettier-eslint --eslint-config-path .eslintrc.custom.js "src/**/*.js"
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# Specify prettier binary path
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prettier-eslint --prettier-path ./node_modules/.bin/prettier "src/**/*.js"
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# Specify prettier config file
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prettier-eslint --config .prettierrc.custom.json "src/**/*.js"
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```
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### Execution Order Control
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Control whether prettier or eslint runs first in the formatting process.
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```bash { .api }
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# Run prettier first, then eslint --fix (default)
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prettier-eslint "src/**/*.js"
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# Run eslint --fix first, then prettier
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prettier-eslint --prettier-last "src/**/*.js"
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```
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### Logging Configuration
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Configure logging levels for debugging and monitoring.
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```bash { .api }
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# Set log level
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prettier-eslint --log-level debug "src/**/*.js"
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prettier-eslint -l warn "src/**/*.js"
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# Available log levels: silent, error, warn, info, debug, trace
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```
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**Log Levels:**
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- `silent`: No output
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- `error`: Only errors
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- `warn`: Errors and warnings (default)
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- `info`: Informational messages
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- `debug`: Debug information
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- `trace`: Verbose debugging
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### Prettier Formatting Options
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Configure Prettier-specific formatting options directly through CLI arguments.
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```bash { .api }
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# Tab/spacing configuration
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prettier-eslint --use-tabs "src/**/*.js"
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prettier-eslint --tab-width 4 "src/**/*.js"
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prettier-eslint --print-width 120 "src/**/*.js"
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# Quote configuration
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prettier-eslint --single-quote "src/**/*.js"
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prettier-eslint --no-single-quote "src/**/*.js"
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# Semicolon configuration
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prettier-eslint --semi "src/**/*.js"
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prettier-eslint --no-semi "src/**/*.js"
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# Trailing comma configuration
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prettier-eslint --trailing-comma es5 "src/**/*.js"
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prettier-eslint --trailing-comma all "src/**/*.js"
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prettier-eslint --trailing-comma none "src/**/*.js"
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# Bracket spacing
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prettier-eslint --bracket-spacing "src/**/*.js"
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prettier-eslint --no-bracket-spacing "src/**/*.js"
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# JSX-specific options
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prettier-eslint --jsx-bracket-same-line "src/**/*.jsx"
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# Arrow function parentheses
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prettier-eslint --arrow-parens avoid "src/**/*.js"
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prettier-eslint --arrow-parens always "src/**/*.js"
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# Parser selection
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prettier-eslint --parser babel "src/**/*.js"
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prettier-eslint --parser typescript "src/**/*.ts"
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# Pragma support
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prettier-eslint --require-pragma "src/**/*.js"
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prettier-eslint --insert-pragma "src/**/*.js"
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# Prose wrapping (for markdown)
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prettier-eslint --prose-wrap always "docs/**/*.md"
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prettier-eslint --prose-wrap never "docs/**/*.md"
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prettier-eslint --prose-wrap preserve "docs/**/*.md"
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```
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**Prettier Option Values:**
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- `--trailing-comma`: `none`, `es5`, `all`
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- `--arrow-parens`: `avoid`, `always`
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- `--parser`: `babel`, `typescript`, `flow`, `json`, `css`, `markdown`, etc.
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- `--prose-wrap`: `always`, `never`, `preserve`
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- Boolean options can be negated with `--no-` prefix
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**Pragma Options Detail:**
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- `--require-pragma`: Only format files containing a special `@format` comment at the top. Useful for gradual adoption in large codebases.
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- `--insert-pragma`: Automatically insert a `@format` pragma comment at the top of formatted files. Works well with `--require-pragma`.
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- `--prose-wrap`: Controls how markdown text wrapping is handled (`always` = wrap at print width, `never` = no wrapping, `preserve` = keep existing wrapping)
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## Exit Codes
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The CLI uses standard exit codes for automation and CI/CD integration:
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```bash { .api }
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# Exit code 0: Success - all files processed without errors
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prettier-eslint "src/**/*.js"
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echo $? # 0
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# Exit code 1: Formatting differences found (with --list-different)
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prettier-eslint --list-different "src/**/*.js" # when files differ from expected format
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echo $? # 1
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# Exit code 1: Formatting errors occurred
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prettier-eslint "src/broken-syntax.js" # when formatting fails due to syntax errors
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echo $? # 1
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# Exit code 1: Configuration or runtime errors
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prettier-eslint --eslint-config-path ./nonexistent.js "src/**/*.js"
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echo $? # 1
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```
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**Exit Code Meanings:**
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- `0`: Success - all operations completed without errors
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- `1`: Failure - formatting errors, syntax errors, configuration issues, or differences found (in `--list-different` mode)
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## Environment Variables
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The CLI supports environment variables for configuration:
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```bash { .api }
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# Set default log level (overrides default "warn")
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LOG_LEVEL=debug prettier-eslint "src/**/*.js"
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LOG_LEVEL=silent prettier-eslint "src/**/*.js"
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# Available values: silent, error, warn, info, debug, trace
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# Equivalent to using --log-level flag
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```
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**Environment Variable Options:**
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- `LOG_LEVEL`: Sets the default logging level (same values as `--log-level`)
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## Integration Examples
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### npm Scripts
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```json
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{
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  "scripts": {
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    "format": "prettier-eslint --write \"src/**/*.{js,jsx,ts,tsx}\"",
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    "format:check": "prettier-eslint --list-different \"src/**/*.{js,jsx,ts,tsx}\"",
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    "precommit": "prettier-eslint --write --list-different \"src/**/*.{js,jsx,ts,tsx}\""
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  }
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}
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```
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### Git Hooks
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```bash
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# .git/hooks/pre-commit
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#!/bin/sh
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prettier-eslint --list-different "src/**/*.js"
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if [ $? -ne 0 ]; then
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  echo "Code formatting issues found. Run 'npm run format' to fix."
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  exit 1
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fi
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```
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### CI/CD Pipeline
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```yaml
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# GitHub Actions example
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- name: Check code formatting
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  run: |
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    npm install
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    npx prettier-eslint --list-different "src/**/*.{js,jsx,ts,tsx}"
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```
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### Editor Integration
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#### Vim Configuration
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```vim
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" Vim configuration - basic formatting with gq command
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autocmd FileType javascript set formatprg=prettier-eslint\ --stdin
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" Auto-format on save (optional)
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autocmd BufWritePre *.js :normal gggqG
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```
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This configuration allows vim users to:
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- Use the `gq` command for manual formatting with prettier-eslint
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- Optionally auto-format JavaScript files on save
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## Configuration Files Support
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prettier-eslint-cli respects standard configuration files:
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- **ESLint**: `.eslintrc.*`, `eslint.config.js`, `package.json` eslintConfig
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- **Prettier**: `.prettierrc.*`, `prettier.config.js`, `package.json` prettier
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- **Ignore Files**: `.eslintignore`, `.prettierignore`
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## Error Handling
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The CLI provides comprehensive error handling and logging:
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- **Individual File Errors**: Logged with full stack traces but don't stop processing other files
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- **Uncaught Exceptions**: Provide debugging steps and issue reporting guidance  
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- **Configuration Errors**: Clear messages about missing or invalid config files
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- **Syntax Errors**: Detailed error information with file locations
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- **Exit Codes**: Returns appropriate exit codes for automation (0 = success, 1 = errors/differences)
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**Common Error Scenarios:**
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- Invalid JavaScript syntax in source files
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- Incompatible ESLint and Prettier rule configurations
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- Missing required dependencies (`prettier-eslint` or fallback)
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- File permission issues preventing read/write operations
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- Invalid glob patterns or file paths
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**Troubleshooting Steps:**
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1. Verify file syntax is valid JavaScript/TypeScript
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2. Check ESLint and Prettier configurations are compatible
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3. Ensure all required dependencies are installed
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4. Verify file permissions allow reading/writing
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5. Use `--log-level debug` for detailed diagnostic information
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## Dependencies
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prettier-eslint-cli requires:
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- **Node.js**: >=16.10.0
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- **Peer Dependency**: `prettier-eslint` (optional, falls back to internal version)
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The package includes an internal fallback version (`@prettier/eslint`) when `prettier-eslint` is not installed.