As a Facebook page admin, you are able to invite people who liked your posts or ads to like your page, this is a cool feature that helps you to grow your page likes for free over time.
I will explain this more further in this post.
However this is a manual process and you have to click the invite button for each person, which can be tedious especially if you get a lot of likes on your posts or ads.
Good news is, that this can be automated with JavaScript.
I have made this bookmarklet that does the clicking for you.
Simply drag and drop the button below into your browsers bookmarks bar to use it.