How to use the @now/build-utils/file-blob.js function in @now/build-utils

fs.writeFileSync(handlerPath, handler, 'utf8')

  console.log()
  console.log('compiling entrypoint with ncc...')
  const ncc = require(path.join(nccPath, 'node_modules/@zeit/ncc'))
  const { code, assets } = await ncc(handlerPath)
  const outputHandlerPath = path.join('user', 'fts-handler.js')

  const blob = new FileBlob({ data: code })
  // move all user code to 'user' subdirectory
  preparedFiles[outputHandlerPath] = blob
  // eslint-disable-next-line no-restricted-syntax
  for (const assetName of Object.keys(assets)) {
    const { source: data, permissions: mode } = assets[assetName]
    const blob2 = new FileBlob({ data, mode })

    preparedFiles[
      path.join('user', path.dirname(entrypoint), assetName)
    ] = blob2
  }

  return {
    preparedFiles,
    handlerPath: outputHandlerPath
  }
}

async function createLambdaForNode(buildConfig, lambdas, workPath) {
  console.log(`Creating lambda for ${buildConfig.name} (${buildConfig.target})`);

  const launcherPath = path.join(__dirname, 'launcher.js');
  let launcherData = await fs.readFile(launcherPath, 'utf8');

  launcherData = launcherData.replace(
    '// PLACEHOLDER',
    [
      `listener = require('./index.js');`,
      'if (listener.default) listener = listener.default;'
    ].join(' ')
  );

  const preparedFiles = {
    'launcher.js': new FileBlob({ data: launcherData }),
    'bridge.js': new FileFsRef({ fsPath: nodeBridge }),
    'index.js': new FileFsRef({
      fsPath: require.resolve(path.join(workPath, buildConfig.outputTo))
    })
  };

  const lambda = await createLambda({
    files: { ...preparedFiles },
    handler: 'launcher.launcher',
    runtime: 'nodejs8.10'
  });

  lambdas[buildConfig.outputTo] = lambda;
}

const handler = `
import * as ftsHttp from 'fts-http'
import * as handler from '${input.replace('.ts', '')}'
const definition = ${definitionData}
export default ftsHttp.createHttpHandler(definition, handler)
`

  fs.writeFileSync(handlerPath, handler, 'utf8')

  console.log()
  console.log('compiling entrypoint with ncc...')
  const ncc = require(path.join(nccPath, 'node_modules/@zeit/ncc'))
  const { code, assets } = await ncc(handlerPath)
  const outputHandlerPath = path.join('user', 'fts-handler.js')

  const blob = new FileBlob({ data: code })
  // move all user code to 'user' subdirectory
  preparedFiles[outputHandlerPath] = blob
  // eslint-disable-next-line no-restricted-syntax
  for (const assetName of Object.keys(assets)) {
    const { source: data, permissions: mode } = assets[assetName]
    const blob2 = new FileBlob({ data, mode })

    preparedFiles[
      path.join('user', path.dirname(entrypoint), assetName)
    ] = blob2
  }

  return {
    preparedFiles,
    handlerPath: outputHandlerPath
  }

// setting up launcher
  const launcherPath = path.join(__dirname, 'launcher.js')
  let launcherData = await fs.readFile(launcherPath, 'utf8')

  launcherData = launcherData.replace(
    '// PLACEHOLDER',
    [
      'process.chdir("./user");',
      `listener = require("${handlerPath}");`,
      'if (listener.default) listener = listener.default;'
    ].join(' ')
  )

  const launcherFiles = {
    'launcher.js': new FileBlob({ data: launcherData }),
    'bridge.js': new FileFsRef({ fsPath: require('@now/node-bridge') })
  }

  const lambda = await createLambda({
    files: { ...preparedFiles, ...launcherFiles },
    handler: 'launcher.launcher',
    runtime: 'nodejs8.10'
  })

  return { [entrypoint]: lambda }
}