Here's some help that I provided a previous user that allowed them to autofill craigslist recently:
Here's a set of rules to get you to the category selection step (add these rules to a new profile if you can to avoid conflicts with existing rules):
[rule 1 - click on the "post to classifieds" link]
Type = JavaScript
Value = document.getElementById('post').click();
[rule 2 - select "for sale by owner"]
Type = Checkbox/Radio
Name = ^fso$
Value = 1
Site = choose type
[rule 3 - click 'continue' button]
Type = JavaScript
Value = document.querySelector('form.picker').submit();
Site = choose type
Here are some things that may not be obvious:
- Remember that the site filter can match either the URL or the page title. Since the craigslist URL seems to be randomly generated, it's more reliable to match against the page title as you can see in rules 2-3.
- I'm auto-submitting (rule 3) by executing submit() on the <form> element, but you could just as easily auto-submit by executing click() on the 'continue' button, like this: document.querySelector('button[value="Continue"]').click();
- document.querySelector() is a great built-in method to have in your toolbox; it basically allows you to select an element using a CSS selector. To quickly see whether a selector selects the element you want, you can execute it in the JavaScript console (press F12 and click on Console tab) and see if it returns that element (it will return null if there is no match). Once you select the element you want, you can either set the value to autofill it (e.g., document.querySelector('#some-input').value = '...') or act on the element (e.g., click or submit as mentioned above).
Hopefully there is enough information here to help you complete the rest of the steps. I have seen reports of some people using Autofill to automate the entire checkout process on Supreme once something is in stock -- crazy stuff!