getFiles.mjs

// @ts-check

import glob from 'glob'

/**
 * @param {string} path
 * @returns {Promise<string[]>}
 */
function getFiles(path) {
  return new Promise((resolve, reject) => {
    glob(path, (error, files) => {
      if (error) {
        reject(error)
        return
      }

      resolve(files)
    })
  })
}

export default getFiles

replace-javascript-to-typescript-extensions.mjs

// @ts-check

import { exec } from 'node:child_process'
import { readFile } from 'node:fs/promises'

import getFiles from './getFiles.mjs'

const paths = await getFiles('./src/**/*.j{s,sx}')

/**
 * @param {string} content
 * @returns {boolean}
 */
function hasJSXExpression(content) {
  const result = /<(\w*)>/gm.exec(content)

  if (result === null) return false

  const [, elementOrComponentName] = result

  return new RegExp(`</${elementOrComponentName ?? ''}>`).test(content)
}

for (const path of paths) {
  const content = await readFile(path, 'utf-8')

  await new Promise((resolve, reject) => {
    const newPath = path.replace(
      /\.js$/,
      hasJSXExpression(content) ? '.tsx' : '.ts'
    )

    exec(`git mv "${path}" "${newPath}"`, (error) => {
      if (error) {
        reject(error)
        return
      }

      resolve(0)
    })
  })

  console.log(path, 'was renamed.')
}