Slate : Slate is a completely customizable framework for building rich text editors.
Slate lets you build rich, intuitive editors like those in Medium, Dropbo...
ProseMirror : In-browser structured text editing component. A toolkit for building rich-text editors on the web.
RequireJS : RequireJS is a JavaScript file and module loader. It is optimized for in-browser use, but it can be used in other JavaScript environments, like Rhino ...
rsvp.js : A lightweight library that provides tools for organizing asynchronous code
meSpeak.js : meSpeak.js (modulary enhanced speak.js) is a 100% client-side JavaScript text-to-speech library
Aloha Editor is an open source WYSIWYG editor that can be used in webpages. Aloha Editor aims to be easy to use and fast in editing, and allows advanced inline editing.