[mcdonje]

>It works by saving a copy of the page you're working on (or any other resource, like a JavaScript or CSS file), letting you edit that, and then serving that file instead of the live version.

1. You can already set up a local host on your machine to run tests. I thought that was standard practice.

2. I'm glad browsers are offering a similar solution which is easier to set up and useful for front end work. I just checked to see if Firefox has similar functionality, and it seems they support diffs for CSS only, but there is an add-on called Resource Override that appears to have similar functionality.

[rasz]

>1. You can already set up a local host on your machine to run tests. I thought that was standard practice.

Yes, run your own local server. You used to be able to just save local copy and click on it. Chrome killed this, now you have to run your own infrastructure even when all you want is testing one letter change.