Avoid referencing local versions of analytics.js and ga.js.
While it's possible to download the JavaScript file (gtag.js) to examine it, storing or serving the JavaScript file locally is not recommended.
Referencing the JavaScript file from Google's servers (i.e., https://www.googletagmanager.com/gtag/js) ensures that you get access to new features and product updates as they become available, giving you the most accurate data in your reports.
