$ npm install @github/quote-selection

<div class="my-quote-region">
  <p>Text to quote</p>
  <textarea></textarea>
</div>

import {Quote} from '@github/quote-selection'

document.addEventListener('keydown', event => {
  if (event.key == 'r') {
    const quote = new Quote()
    if (quote.closest('.my-quote-region')) {
      quote.insert(document.querySelector('textarea'))
    }
  }
})

const quote = new MarkdownQuote('.comment-body')
quote.select(document.querySelector('.comment-body'))
if (quote.closest('.my-quote-region')) {
  quote.insert(quote, document.querySelector('textarea'))
}

npm install
npm test

Watchers

quote(selection.toString(), selection.getRangeAt(0), {
  prepend: 'before quote', 
  append: 'after quote' 
})

before quote

> intelligent thing that was quoted

after quote