What’s the quickest, easiest way to execute a JavaScript file on a live web page?

Question

I have this JavaScript file URL:

https://rawgit.com/Khan/tota11y/master/build/tota11y.min.js

(hosted on GitHub and passed through RawGit), and I would like to inject it into a live web page via the browser’s console.

In order to achieve that, I can dynamically create a <script> element and append it to the DOM:

(function () {
  var s = document.createElement('script');
  s.src = 'https://rawgit.com/Khan/tota11y/master/build/tota11y.min.js';
  document.body.appendChild(s);
}())

But this is neither quick nor easy. I would like to use an API that makes this possible via a simple invocation, e.g.:

exec('https://rawgit.com/Khan/tota11y/master/build/tota11y.min.js')

Do Chrome or Firefox provide such an API (or anything similar) in their console?

---

Use case: Quickly testing JavaScript libraries hosted on GitHub on live web pages.

Answer 1

Update: The Developer Toolbar has been removed from Firefox Nightly as of 18th May 2018.

In Firefox, you can inject scripts using the Developer Toolbar. Bring it up withShift+F2 and type inject https://rawgit.com/Khan/tota11y/master/build/tota11y.min.js

More info on MDN