extract-location-data.js

const fs = require('fs')
const JSONStream = require('JSONStream');
var es = require('event-stream');
const filePath = './location-history.json'
const fileOutputPath = './transform-location-history.js'

const fileStream = fs.createReadStream(filePath);
const fileOutputStream = fs.createWriteStream(fileOutputPath)

let index = 0;
const  transformer = (data) => {
  const location = {
        latitude: data.latitudeE7 / 10000000,
        longitude: data.longitudeE7 / 10000000
    };
  let result = JSON.stringify(location) + ',';
  if (index === 0) {
    result = 'const locationHistory = [' + result
  }
  index++;
  if (index < 100)
    fileOutputStream.write(result);
}

const end = () => {
  const finish = ']; export default locationHistory\n'
  fileOutputStream.write(finish, () => {
    fileOutputStream.close()
  })
  console.log(`${index} objects are written to file`)
}

fileStream
.pipe(JSONStream.parse('locations.*'))
.pipe(es.through(transformer, end))