In the last chapter, we learned how promises were implemented in Angular.js and how they provided benefit in the fast growing real-time web app industry. In this chapter, we will explore another very famous and useful JavaScript library for frontend web/mobile apps development.

jQuery is one the most used JavaScript libraries and it is recognized as one of the most maintainable, progressive, and easy to adopt libraries around. jQuery has also a credit to shrink the mile-long lines of code into plainer and simpler short code. This utility helped jQuery gain popularity beyond imagination. In this chapter, we will be looking at the history of jQuery, how it evolved, what is the basic way to use it, and how promises are playing a part in the maturity of jQuery. Let's start with the history of jQuery in brief.