Anime.js is a fast, multipurpose and lightweight JavaScript animation library with a simple, yet powerful API.
It works with CSS properties, SVG, DOM attributes and JavaScript Objects.

Svelte is a radical new approach to building user interfaces. Whereas traditional frameworks like React and Vue do the bulk of their work in the browser, Svelte shifts that work into a compile step that happens when you build your app.

Instead of using techniques like virtual DOM diffing, Svelte writes code that surgically updates the DOM when the state of your app changes.

Vue.js is a library for building interactive web interfaces. It provides data-reactive components with a simple and flexible API. Core features include:

Dead simple, unobtrusive reactivity using plain JavaScript objects.
Component-oriented development style with tooling support
Lean and extensible core
Flexible transition effect system
Fast without the need for complex optimization

Library to detect when DOM elements become visible and disappear on scroll.

Want to use Vanilla JS but find native APIs a bit unwieldy? Bliss is for you

Zepto is a minimalist JavaScript library for modern browsers with a largely jQuery-compatible API. If you use jQuery, you already know how to use Zepto.

DOM Monster is a cross-platform, cross-browser bookmarklet that will analyze the DOM & other features of the page you're on, and give you its bill of health.

A passive reconnaissance tool inside the DOM (experimental)

DOM Storage Query Language (DomSQL) is an SQL inspired interface for DOM Storage (or Web Storage as defined in the W3C working draft).

The modular lightweight JavaScript library, with CSS selectors, event handling, AJAX and complete Unicode support

Easy Ajax and DOM manipulation for dynamic web applications