This document provides a quick start guide to JavaScript frameworks for developing SharePoint apps. It introduces several popular JavaScript frameworks and libraries including jQuery, Bootstrap, LESS, and Modernizr. jQuery is described as the most popular JavaScript library for easier DOM element selection and AJAX calls. Bootstrap is explained as an open-source framework for developing responsive, mobile-first projects with pre-built CSS and JavaScript components. LESS and SASS are defined as languages that extend CSS with features like variables and mixins. The document also covers validation plugins, polyfills/shims, and provides demo code examples of Bootstrap and validation in SharePoint apps.