title: How do you create custom toolbar buttons in QuillJS?
body: <p>I'm using QuillJS in my application (1.0.0-beta.8) and I'm trying to extend its functionality by adding two new buttons in the toolbar. Specifically, when the user clicks on either button, an element is injected into the text area, with some CSS styling to look like a small box containing predefined text. A user can click on that box and I should be able to handle that event (changing the text and sending an Ajax request for example)</p>
  
  <p>The docs are somewhat incomplete, do I need to create a <code>Format</code> or something?</p>