https://github.com/Suleman-Elahi/WACopyMate

WACopyMate is a dead simple Chrome/Firefox add-on to copy contact numbers from chats on WhatsApp Web in 1 click. With this, you will not have to manually copy numbers, remove spaces, and remove parenthesis. Just tap on the ad-don's icon in the toolbar to copy number of the contact in currently opened chat.

It is my first attempt at creating browser extensions.