Deep Dive into Functional JavaScript

ES6/ES2015 is introduced from a functional perspective, so that we can build on these fundamentals to write clear, compact functional code.

Using immutable data structures is a cornerstone of functional programming. Yet, the JavaScript support for immutability is not that obvious. This video raises awareness on the different types of cloning, and makes sure we don’t end up mutating our data.

Functional programming techniques are mixed with other techniques in JavaScript. When it comes to handling events, timeouts, and other callbacks, we have to use techniques to connect functional code with its context. This video demonstrates how context binding is used as a connector.

Reading pure functional code is often a riddle. We increase readability with object-oriented and functional techniques: chaining and function composition.

JavaScript functions are values. Therefore, functions can be passed to other functions, and they can also be return values of functions. This is how we create higher order functions, giving us a powerful way to write loops and callbacks in functional style. 

In functional programming, we often use higher order functions on arrays instead of using loops. Therefore, it is beneficial to learn about ways of handling JavaScript arrays.

Even though forEach looks like a functional utility, it is not usable when our goal is to write side-effect free code. We should still substitute loops with proper functional constructs. Therefore, it is now time to introduce the map, reduce, and filter operations.

We will take some SQL SELECT statements and translate them to queries written using JavaScript higher order functions such as map, reduce, and filter. You will not only learn how to perform inner joins of two tables but you will also see an example performing a left join. We will also learn how to group our results.

SQL queries often contain filtering conditions. As we will see filtering in action, we will first implement the filter function using reduce. Then we will apply various conditions on our queries to filter our results. We will filter regular joins as well as aggregated results.

This practical exercise will make you think out of the box a bit for understanding how advanced reduce functions can be implemented. We will use the reduce function to create a tree data structure from an array of nodes.

You will learn some basic definitions and JavaScript constructs that we will use throughout the rest of the section.

 When writing higher order functions in functional style, you will often encounter the technique of currying. You will also need to understand currying for the purpose of understanding a partial application.

We will start with a comparison between currying and partial application. We will then implement partial application in JavaScript. After the implementation, we will revisit the bind function of JavaScript for the purpose of partially applying arguments of a function. We will conclude this video with writing a partially applied map function.

We will use the principles of partial application in this section to implement a template renderer in JavaScript without using any external libraries.

You will learn what recursion is in mathematics and in software development. You will also find out about different types of recursion. At the end of this section, we will see how to transfer iterative solutions to recursive solutions using accumulator variables.

This section introduces some optimization techniques combating the drawbacks of using recursion. These optimization techniques are mixing functional and non-functional elements of JavaScript, tail call optimization, and memoization.

You will review the main points learned in this volume in order to place them in your functional programming utility belt.

In this last video, you will construct a learning plan for yourself based on your own goals. You will also get some recommendations that will accelerate your learning curve.