@gameroom/cli/src/helpers/incrementFileName.js

A command line tool for Gameroom

const { existsSync } = require('fs'),
  { extname } = require('path')

module.exports = (path) => {
  let i = 0
  while (existsSync(path)) {
    // get extension
    const ext = extname(path)
    // remove extension
    path = path.replace(ext, '')
    // remove number
    if (i) path = path.replace(`_${i}`, '')
    // increment number
    i++
    // add number and ext
    path = `${path}_${i}${ext}`
  }
  return path
}