Custom Formatters

/**
 * Enhanced ESLint formatter with fix previews and rule documentation
 * @param results - Array of ESLint results from linting process
 * @returns Formatted string output for display
 */
function stylishFixesFormatter(results: ESLintResult[]): string;

interface ESLintResult {
  /** Path to the file that was linted */
  filePath: string;
  /** Array of ESLint messages (violations) */
  messages: ESLintMessage[];
  /** Number of error-level violations */
  errorCount: number;
  /** Number of warning-level violations */
  warningCount: number;
  /** Source code of the file (if available) */
  source?: string;
}

interface ESLintMessage {
  /** Line number of the violation */
  line: number;
  /** Column number of the violation */
  column: number;
  /** ESLint rule ID that was violated */
  ruleId: string;
  /** Human-readable violation message */
  message: string;
  /** Severity level (1 = warning, 2 = error) */
  severity: 1 | 2;
  /** Automatic fix information (if available) */
  fix?: ESLintFix;
}

interface ESLintFix {
  /** Character range to replace [start, end] */
  range: [number, number];
  /** Text to insert at the specified range */
  text: string;
}

// Using with ESLint CLI
npx eslint --format node_modules/eslint-plugin-github/lib/formatters/stylish-fixes.js src/

// Using in package.json entry point
import stylishFixesFormatter from "eslint-plugin-github/lib/formatters/stylish-fixes.js";

// Process ESLint results
const formattedOutput = stylishFixesFormatter(eslintResults);
console.log(formattedOutput);

/**
 * Formatter output features and capabilities
 */
interface FormatterFeatures {
  /** Display relative file paths from project root */
  relativeFilePaths: boolean;
  
  /** Show rule documentation URLs when available */
  ruleDocumentationLinks: boolean;
  
  /** Display diff previews for fixable violations */
  fixPreviews: boolean;
  
  /** Show fix commands for automated repairs */
  fixCommands: boolean;
  
  /** Provide violation statistics summary */
  statisticsSummary: boolean;
  
  /** Use Unicode symbols for enhanced display */
  unicodeSymbols: boolean;
}

src/components/Button.js
23:15 github/no-blur  (https://github.com/github/eslint-plugin-github/blob/main/docs/rules/no-blur.md)
	Do not use element.blur(), instead restore the focus of a previous element.

45:8 github/no-inner-html  (https://github.com/github/eslint-plugin-github/blob/main/docs/rules/no-inner-html.md)
	innerHTML usage can lead to XSS vulnerabilities.


$ eslint --fix src/components/Button.js
--- src/components/Button.js
+++ src/components/Button.js
@@ -42,7 +42,7 @@
   handleClick() {
     this.processAction();
-    element.innerHTML = '<span>Processing...</span>';
+    element.textContent = 'Processing...';
   }


✖ 2 problems (2 errors, 0 warnings)

/**
 * Rule documentation integration functionality
 */
interface RuleDocumentationIntegration {
  /** Get documentation URL for a specific rule */
  getRuleDocumentationURL(ruleId: string): {
    found: boolean;
    url?: string;
  };
  
  /** Display rule links in formatted output */
  displayRuleLinks: boolean;
  
  /** Support for custom rule documentation URLs */
  customRuleURLs?: Record<string, string>;
}

/**
 * Fix preview and diff generation
 */
interface FixPreviewGeneration {
  /** Generate diff preview for fixable violations */
  generateDiffPreview(
    originalSource: string,
    fixedSource: string
  ): string;
  
  /** Apply ESLint fixes to source code */
  applyFixes(source: string, messages: ESLintMessage[]): {
    output: string;
    fixed: boolean;
  };
  
  /** Create temporary files for diff comparison */
  createDiffFiles(original: string, fixed: string): {
    originalPath: string;
    fixedPath: string;
  };
  
  /** Execute system diff command */
  executeDiffCommand(fileA: string, fileB: string): string;
}

$ eslint --fix src/utils/helpers.js
--- a/src/utils/helpers.js
+++ b/src/utils/helpers.js
@@ -15,8 +15,8 @@
 function processItems(items) {
-  items.forEach(item => {
-    processItem(item);
-  });
+  for (const item of items) {
+    processItem(item);
+  }
 }

/**
 * Statistics and summary generation
 */
interface StatisticsGeneration {
  /** Calculate total violations across all files */
  calculateTotalViolations(results: ESLintResult[]): {
    totalProblems: number;
    totalErrors: number;
    totalWarnings: number;
  };
  
  /** Generate summary line with Unicode symbols */
  generateSummaryLine(errors: number, warnings: number): string;
  
  /** Handle pluralization for summary text */
  pluralize(word: string, count: number): string;
  
  /** Format final statistics output */
  formatStatistics(
    total: number,
    errors: number,
    warnings: number
  ): string;
}

✖ 1 problem (1 error, 0 warnings)
✖ 15 problems (8 errors, 7 warnings)
✓ No problems found

/**
 * File processing pipeline for formatter
 */
interface ProcessingPipeline {
  /** Initialize output buffer */
  initializeOutput(): string;
  
  /** Process each file's results */
  processFileResults(result: ESLintResult): string;
  
  /** Format individual violation messages */
  formatViolationMessage(message: ESLintMessage): string;
  
  /** Generate fix previews for fixable violations */
  generateFixSection(result: ESLintResult): string;
  
  /** Append final statistics */
  appendStatistics(
    totalErrors: number,
    totalWarnings: number
  ): string;
}

interface FormatterConfiguration {
  /** Project root path for relative file paths */
  rootPath?: string;
  
  /** Whether to show rule documentation URLs */
  showRuleURLs?: boolean;
  
  /** Whether to show fix previews */
  showFixPreviews?: boolean;
  
  /** Custom diff command (defaults to 'diff') */
  diffCommand?: string;
  
  /** Diff context lines (defaults to 5) */
  diffContext?: number;
}

interface DiffResult {
  /** Diff output string */
  output: string;
  /** Whether diff was successful */
  success: boolean;
  /** Any error message */
  error?: string;
}

interface FormatterOutput {
  /** Total formatted output string */
  output: string;
  /** Number of files processed */
  filesProcessed: number;
  /** Total violations found */
  totalViolations: number;
  /** Whether any fixes were available */
  hasFixableViolations: boolean;
}