History.js
History.js gracefully supports the HTML5 History/State APIs (pushState, replaceState, onPopState) in all browsers. Including continued support for data, titles, replaceState. Supports jQuery, MooTools and Prototype. For HTML5 browsers this means that you can modify the URL directly, without needing to use hashes anymore. For HTML4 browsers it will revert back to using the old onhashchange functionality.
Garlic.js
Garlic.js allows you to automatically persist your forms' text and select field values locally, until the form is submitted. This way, your users don't lose any precious data if they accidentally close their tab or browser.
Do T
The fastest + concise javascript template engine for nodejs and browsers. Partials, custom delimiters and more.
Hitch
A lightweight engine that allows you to hitch new capabilities to the browser (prollyfill).
Countable
Countable is a JavaScript function to add live paragraph-, word- and character-counting to an HTML element.
Pickadate.js
lightweight jquery date selector with multi-language support
Magnific Popup
Light and responsive lightbox plugin with focus on performance.
Intro.js
A better way for new feature introduction and step-by-step users guide for your website and project.
Bluebird
Bluebird is a full featured promise library with unmatched performance.
Bacon.js
FRP (functional reactive programming) library for Javascript
Datedropper
datedropper is a jQuery plugin that provides a quick and easy way to manage dates for input fields.
Tiny Color
Fast, small color manipulation and conversion for JavaScript
Messenger
Growl-style alerts and messages for your app. #hubspot-open-source
Bignumber.js
A JavaScript library for arbitrary-precision decimal and non-decimal arithmetic
Nightwatch
UI automated testing framework based on node.js and selenium webdriver
Zenscroll
A JavaScript module to smooth-scroll web pages and other scrollable elements
Gator
Event delegation in Javascript