prettify changed ts(x) files

prettifyChanged.js

const fs = require('fs')
const path = require('path')
const shell = require('shelljs')
const prettier = require('prettier')
const args = process.argv
const doGitAdd = args.includes('--git-add') || args.includes('-ga')
const FILTER_PATTERN = /\.tsx?$/

shell.config.silent = true
const changedFiles = shell.exec('git status --porcelain=v1 -z')

// get filenames (except for deleted items)
const lines = changedFiles.split('\0')
const filenames = []
for (let i = 0; i < lines.length; i++) {
  const line = lines[i]
  const flags = line.substr(0, 2)
  const filename = line.substr(3)
  if (!flags.includes('D') && FILTER_PATTERN.test(filename)) {
    filenames.push(path.resolve(__dirname + `/../../${filename}`))
  }
  if (flags.includes('R')) {
    i++
  }
}

// run prettier if needed
filenames.forEach(fn => {
  fs.readFile(fn, 'utf-8', (error, text) => {
    if (error) {
      console.error('File read error', error)
      return
    }
    prettier.resolveConfig(fn).then(options => {
      options = Object.assign(options, { parser: 'typescript' })
      const shortFn = path.basename(fn)
      if (prettier.check(text, options)) {
        console.log(`${shortFn} - already formatted`)
      } else {
        console.log(`${shortFn} - reformatting`)
        fs.writeFile(fn, prettier.format(text, options), (error) => {
          if (error) {
            console.error('File write error', error)
            return
          }
          if (doGitAdd) {
            shell.exec(`git add "${fn}"`)
          }
        })
      }
    }).catch(error => {
      console.error('Prettier config resolver error', error)
    })
  })
})