Check if file identical after download

I am making a Twitter bot that get an image from URL and post to Twitter.

I have set the interval for getPhoto() to run every 1 minute.

After the image is saved, the bot needs to check if the image is updated before it uploads to Twitter.

Below is my current code.

const Twit = require('twit')
const request = require('request')
const fs = require('fs')
const config = require('./config')
const moment = require('moment');

const os = require('os')
const tmpDir = os.tmpdir()

const bot = new Twit(config)

function getPhoto(fileName) {
  const url = 'http://blabla.com/pic.jpg'
  const descriptionText = 'Latest Image Now'
  const filePath = tmpDir + "/" + fileName
  const file = fs.createWriteStream(filePath);
  request(url).pipe(file).on('close', err => {
    if (err) {
      console.log(err)
    } else {
      uploadMedia(descriptionText, filePath)
    }
  })
}

function uploadMedia(descriptionText, filePath) {
  bot.postMediaChunked({ file_path: filePath }, (err, data, response) => {
    if (err) {
      console.log(err)
    } else {
      var params = { status: descriptionText, media_ids: [data.media_id_string] }
      bot.post('statuses/update', params, (err, data, respone) => {
        if (err) {
          console.log(err)
      })
    }
  })
}

getPhoto('pic.jpg');

setInterval(getPhoto, 1000*60, 'pic.jpg')

via PolarBear