You will get an in-depth overview of how to handle asynchronous code with promises, generator functions, and the ES2017 async-await construct. These tools will help you set up communication with a server via an API later, when implementing a web application.

Lazy evaluation will allow you to optimize performance of retrieving a collection of data, where you may need to process and retrieve just a fraction of the available elements. This powerful technique will not only allow you to write performant code, but it also makes it possible for you to handle infinite sequences.

We will also implement a web application together, demonstrating the practical usage of most of the features you learned in this course, and in the previous volume of this course, Deep Dive into Functional javascript. You will see higher order functions, currying, partial evaluation, recursion, ES6, asynchronous code with promises and ES2017 async-await, and many more language construct and functional programming ideas in practice. While we anchor these techniques into your mind with the repeated practical usage, you will also learn about techniques to write maintainable software: test driven development, top-down design, and bottom-up design. We will use Mocha and ChaiJs to write unit tests for the functional part of the application