BuildOutput

interface BuildOutput

• logs: BuildMessage | ResolveMessage[]
• metafile?: BuildMetafile

  Metadata about the build including inputs, outputs, and their relationships.

  Only present when BuildConfig.metafile is true.

  The metafile contains detailed information about:

  • inputs: All source files that were bundled, their byte sizes, imports, and format
  • outputs: All generated output files, their byte sizes, which inputs contributed to each output, imports between chunks, and exports

  This can be used for:

  • Bundle size analysis and visualization
  • Detecting unused code or dependencies
  • Understanding the dependency graph
  • Integration with bundle analyzer tools

  const result = await Bun.build({
    entrypoints: ['./src/index.ts'],
    outdir: './dist',
    metafile: true,
  });
  
  if (result.metafile) {
    // Analyze input files
    for (const [path, input] of Object.entries(result.metafile.inputs)) {
      console.log(`${path}: ${input.bytes} bytes, ${input.imports.length} imports`);
    }
  
    // Analyze output files
    for (const [path, output] of Object.entries(result.metafile.outputs)) {
      console.log(`${path}: ${output.bytes} bytes`);
      for (const [inputPath, info] of Object.entries(output.inputs)) {
        console.log(`  - ${inputPath}: ${info.bytesInOutput} bytes`);
      }
    }
  
    // Write to disk for external analysis tools
    await Bun.write('./dist/meta.json', JSON.stringify(result.metafile));
  }
  
• outputs: BuildArtifact[]
• success: boolean