takeout

let dataToWrite = '';
const fs = require('fs');
const testData = require('./your/takeout/file.json')

for (item in testData.locations){
	let lat = String(testData.locations[item].latitudeE7).substr(0, (String(testData.locations[item].latitudeE7).length - 7)) + '.' + String(testData.locations[item].latitudeE7).substr((String(testData.locations[item].latitudeE7).length - 7)) 
	let lng = String(testData.locations[item].longitudeE7).substr(0, (String(testData.locations[item].longitudeE7).length - 7)) + '.' + String(testData.locations[item].longitudeE7).substr((String(testData.locations[item].longitudeE7).length - 7)) 

	dataToWrite = dataToWrite + `${testData.locations[item].timestampMs},${lat},${lng}\n`
}

fs.writeFile('what-you-want-t0-call-it.csv', dataToWrite, 'utf8', function (err) {
  if (err) {
    console.log('Some error occured - file either not saved or corrupted file saved.');
  } else{
    console.log('it saved');
  }
});

this converts the takeout json file into a CSV file you can load in your GIS software and plot the lat/lng with timestamp.

A lot of other cool data is stripped out. resulting CSV is way smaller than the huge json file