I know that there are several ways to import your Facebook contacts to Gmail, one of which includes first importing them into Yahoo, and then exporting the address book, and then importing it into Gmail. However, that process is pretty long.
If you really want to import your Facebook contacts to Gmail, a Google Chrome extension will come in pretty handy. The Chrome extension called Facebook Friends Exporter provides users with an option to export their friends information from Facebook as a CSV file. The information you can export includes your Friend’s name, emails, phone numbers, screen names and websites. The good part about the extension though is that it also allows you to import these contacts into Gmail in a single click.
Once you have installed the extension, you will see an addition menu item called "Export friends!" in Facebook. Clicking the link will advice you to go to your friends page, however, the extension can also do that automatically for you.
On the next page, you will be shown a message about Facebook owning your friends and disclaimers which you have to accept. Once you do that, you can Get started with importing your friends and storing it locally.
The extension will then cache all your friends in Google Chrome and start importing them one by one. The process might take a while if you have a lot of friends and takes breaks in between (after it has accessed 60 of your friends profiles, otherwise Facebook will start displaying images for email address). Once the entire import process has been completed, you will be given an option to import your Facebook contacts into Gmail.
Facebook has been very strict about any script accessing contact information about your friends and have even banned users, so you might want to tread with caution here. Nevertheless, the script works and it’s hassle free, so go ahead and try it out if you really want to import your Facebook contacts to Gmail.