Fetch firebase REST API data and save to .json file

fetch-firebase-data.js

const fetch = require('node-fetch')
const fs = require('fs')

const config = {
  endpoint: 'https://FIREBASE_PROJECT.firebaseio.com/',
  pathsToFetch: [
    // database nodes
    'pages',
    'posts'
  ],
  dataFileName: './src/data.json'
}

const writeFile = ({filename, data}) => {
  console.log(`Writing file ${filename}`)
  fs.writeFileSync(filename, JSON.stringify(data, null, 2))
  console.log(`Writing file ${filename} Complete ✅`)
}

const reduceArrayToObject = (dataObj, data) => ({
  ...dataObj,
  ...data
})

const fetchData = () => {
  if (!config.endpoint) return console.error(`Please add 'REACT_APP_FIREBASE_ENDPOINT' to .env`)

  const fetchPromises = config.pathsToFetch.map(
    path => {
      console.log(`Fetching ${config.endpoint + path}`)
      return fetch(config.endpoint + path + '.json')
        .then(response => response.json())
        .then(data => {
          console.log(`Fetching ${config.endpoint + path} Complete ✅`)
          return data
        })
        .then(data => ({ [path]: data }))
    }
  )

  Promise.all(fetchPromises)
    .then(dataArr => dataArr.reduce(reduceArrayToObject, {}))
    .then(data => writeFile({
      data,
      filename: config.dataFileName
    }))
    .catch(console.error)
}

fetchData()