Simple javascript snippet to enable quote sharing (medium-style) on any website or blog

I wish I could find a better way to express the idea. I’m all ears:

When the user selects any text on the page, a share button pops up which encourages the user to share that selected text on Facebook or Twitter (with a link back to the article)

It’s easiest to understand it by trying it. It’s installed on that page https://preactive.chat

Do you have any ideas how I could message this better?