A JavaScript framework is a library of pre-written code that allows for easy development of JavaScript-based applications. The most popular frameworks are jQuery, AngularJS, ReactJS, and Vue.js. Each framework has its own pros and cons, so it’s important to choose the right one for your project.

jQuery is the most popular JavaScript framework and is used by over 70% of all websites. It’s easy to learn and has a wide range of plugins available. However, it’s not as fast as some of the other frameworks and can be difficult to debug.

AngularJS is a full-fledged MVC framework developed by Google. It’s great for large projects and has a lot of features, but it can be challenging to learn and use.

ReactJS is a declarative, component-based framework developed by Facebook. It’s efficient and fast, but uses a different programming paradigm than other frameworks which can make it difficult to learn.

Vue.js is an open source framework similar to ReactJS that aims to be simple and lightweight. It’s easy to learn and use, but doesn’t have as many features as some of the other frameworks.