How to implement a browser extension with interaction with the browser console and website api?

Question

JavaScript

You need to create an extension for Opera, Chrome, Yandex, Safari, Firefox browsers, which was executed only on the pages of the shutterstock.com site and displayed keywords in the extension field taken from the page for copying to the user.
If this is the code

var array = [];
$('.btn-search-pill').each(function() {array.push($(this).text())});
array.join(', ');

send in the console, for example, on this page , then the site will return the keywords in response. And I want these words to be inserted into the extension field (when the user clicks on the extension icon in their panel), as well as a reload button for the extension.
How to implement this? How to reload an extension on a button?