Stop mobile network proxy from injecting JavaScript

Question

I am using a mobile network based internet connection and the source code is being rewritten when they present the site to the end user.

In the localhost my website

Answer 1

I'm suprised no one has put this as answer yet. The real solution is:

USE HTTPS!

This is the only way to stop ISPs (or anyone else) from inspecting all your traffic, snooping on your visitors, and modifying your website in flight.

With the advent of Let's Encrypt, getting a certificate is now free and easy. There's really no reason not to use HTTPS in this day and age.

You should also use a combination of redirects and HSTS to keep all of your users on HTTPS.