The logger option provides custom logging for React Compiler events during compilation.

{
  logger: {
    logEvent(filename, event) {
      console.log(`[Compiler] ${event.kind}: ${filename}`);
    }
  }
}

Reference

logger

Configures custom logging to track compiler behavior and debug issues.

Type 

{
  logEvent: (filename: string | null, event: LoggerEvent) => void;
} | null

Default value

null

Methods

  • logEvent: Called for each compiler event with the filename and event details

Event types

  • CompileSuccess: Function successfully compiled
  • CompileError: Function skipped due to errors
  • CompileDiagnostic: Non-fatal diagnostic information
  • CompileSkip: Function skipped for other reasons
  • PipelineError: Unexpected compilation error
  • Timing: Performance timing information

Caveats

  • Event structure may change between versions
  • Large codebases generate many log entries

Usage

Basic logging

Track compilation success and failures:

{
  logger: {
    logEvent(filename, event) {
      switch (event.kind) {
        case 'CompileSuccess': {
          console.log(`✅ Compiled: ${filename}`);
          break;
        }
        case 'CompileError': {
          console.log(`❌ Skipped: ${filename}`);
          break;
        }
        default: {}
      }
    }
  }
}

Detailed error logging

Get specific information about compilation failures:

{
  logger: {
    logEvent(filename, event) {
      if (event.kind === 'CompileError') {
        console.error(`\nCompilation failed: ${filename}`);
        console.error(`Reason: ${event.detail.reason}`);

        if (event.detail.description) {
          console.error(`Details: ${event.detail.description}`);
        }

        if (event.detail.loc) {
          const { line, column } = event.detail.loc.start;
          console.error(`Location: Line ${line}, Column ${column}`);
        }

        if (event.detail.suggestions) {
          console.error('Suggestions:', event.detail.suggestions);
        }
      }
    }
  }
}
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