JavaScript

How to make a word replacement Chrome extension

I recently made the ‘Brexit means Breadsticks’ Chrome extension that replaces all mentions of the word ‘Brexit’ with ‘Breadsticks’. Here’s how you can make a similar word replacement extension for Chrome.

First of all, here is the code for it on GitHub. Feel free to use it however you like.

If you’re still reading this, here is how I went about this. This was trickier than I expected, and I didn’t want to use code I found online to do this because, well, it was a weekend project I made for fun and sticking someone else’s code in and calling it a day isn’t as much fun. Also, I’d be lying if I said I understood everything that the ‘cloud to butt’ code did.

Act 1: Failure

This is what I tried at first:

const words = [...document.body.getElementsByTagName('*')];

  const strip = words.forEach(element => {
      element.innerHTML.replace(/Brexit/gi, 'Breadsticks');
  });

Note to self: .replace() does not modify the existing variable, so you need to re-assign it to work.

I also tried

document.body.innerHTML = document.body.innerHTML.replace(/Brexit/gi, 'Breadsticks');

Which I thought was clever. But it kind of breaks the internet if you’re running this code on all pages you load. This will strip off .addEventListener() at best, and break a whole bunch of things I’m not even sure about at worst.

Act 2: Frustration & More Failure

So, my hypothesis here was that, select all the elements on a page using getElementsByTagName('*') and then loop through it to find the word I’m looking to replace, and then use regex to do the global replacement. Sounds simple enough. But it wouldn’t work. Arghhh.

Act 3: Redemption

I got some help from a senior developer at work. I wasn’t way off. What I needed to do was nest another .forEach() loop inside my .forEach() loop to look inside the nodes I was looping over. Then, select only the ones with nodeType == 3 which are the text nodes, and THEN run the regex text replacement.

Here’s the working code. Seeing it work without breaking brought a tear to my eye.