How does Facebook disable the browser's integrated Developer Tools?

Question

So apparently because of the recent scams, the developer tools is exploited by people to post spam and even used to \"hack\" accounts. Facebook has blocked the developer too

Answer 1

Internally devtools injects an IIFE named getCompletions into the page, called when a key is pressed inside the Devtools console.

Looking at the source of that function, it uses a few global functions which can be overwritten.

By using the Error constructor it's possible to get the call stack, which will include getCompletions when called by Devtools.

---

Example:

const disableDevtools = callback => {
  const original = Object.getPrototypeOf;

  Object.getPrototypeOf = (...args) => {
    if (Error().stack.includes("getCompletions")) callback();
    return original(...args);
  };
};

disableDevtools(() => {
  console.error("devtools has been disabled");

  while (1);
});