Write a TypeScript barrel file from files found in directory

barrel.js

const path = require('path')
const fs = require('fs')
const source = process.env.PWD
const filenames = fs.readdirSync(source)
.filter(filename => filename.indexOf('.ts') !== -1 && filename !== 'index.ts')
.map(filename => filename.replace('.ts', ''))
const content = filenames
.map(filename => `export * from './${filename}'`)
.join('\n')
fs.writeFileSync(path.join(source, 'index.ts'), content, { encoding: 'utf8' })
console.log(`wrote to ${source}/index.ts`)