Gain insights into intermediate JavaScript, mastering interview questions, common design patterns, and deep understanding of the language. Learn with expert Arnav Aggarwal's engaging teaching method.

This is for those familiar with the basics of JavaScript and looking to advance their knowledge and really understand how the language works. We'll cover topics that are essential to help you read, understand, and write better code. Before starting, you should be familiar with the basics of variables, functions, and loops in JavaScript.

This course will enable you to master JavaScript interview questions that stump most developers. You'll be able to talk intelligently about the fundamentals of the language and about common design patterns.

This course has been created by Arnav Aggarwal, a full-stack engineer. Having attended a coding boot camp and having taught at another one, Arnav has extensive experience understanding how new developers learn to code. In under a month, Arnav's published articles on JavaScript concepts have received over 50,000 views and have been featured as staff selections on Medium.com and codementor.io because of their educational value.

Yangshun Tay

In response to "The Complete Rules to 'this'": 
Clear and to the point. This is one of the best explanations on “this” available on the net. I particularly liked how you explained about global function invocation being implicit method invocation on window. Thank you.

Front-End Engineer at Facebook

Jaya Arasalike

This is an excellent javascript course. Arnav covers deep basics well by giving enough examples and explaining what exactly is happening - how/ when values are changing. His diagrams, for example local vs global scope or the table representation for values vs reference makes reader easily understand what he is talking about and how it works. The quizzes at the end of each chapter, makes one think through what he or she has learnt and apply those concepts to arrive at the answers. That helps a lot in nailing down the core concepts. 

Bootcamp Graduate & Full-Stack Developer

Irshaad Bijan Adatia

In response to the Prototypes & Inheritance articles:

Having just finished a JavaScript course in college, this was a great stepping stone to move into an intermediate level if JS. Thank you.

It was also very well laid out.

Computer Science Student

Step Up Your JS: A Comprehensive Guide to Intermediate JavaScript

# ES 2015

## Changes

JavaScript added a whole slew of functionality to the language in 2015. These are tools intended to make the language easier, more powerful, and more robust. Code that we've been writing up until now can be written faster and cleaner. Problems such as variable hoisting and callback hell are solved.

Job interviews will also feature questions based on ES5 JavaScript. You'll be asked questions about scope and hoisting that you wouldn't be aware of if you'd started by using the new tools we're about to go over.

These new features won't change your world, but they'll make code a little less painful in general. There are little things, like trailing commas in function parameters. Whereas before `function(a, b,) {}` would throw a syntax error, it's now allowed.

There are also big things that will change every piece of code you write, like new ways to declare variables, which we've already discussed.

Nothing in ES2015+ is vital to building websites. For years, people have built sites with just what we've already covered so far. You could stop right here and skip the rest of the course and you'd have everything needed to build websites. This just makes it all a little easier.

# Frameworks

While ES2015 isn't necessary for web development, if you'd like to use a modern framework, it's essentially a requirement. React.js and Angular both rely heavily on ES2015 features and without them, you'll have trouble finding online help such as documentation and answers to questions.

# Browser Implementations

Many browsers are slow to implement new JavaScript features. In terms of ES2015, virtually every modern browser has implemented everything. For ES2016 & newer, Chrome, Firefox, and Safari will adopt new functionality at different times.

This problem has given rise to *transpilers*. A transpiler will process bleeding-edge code and transform/compile it down into ES5 code so that it works on any browser, even older versions of Internet Explorer. Several websites are now written with cutting-edge features and the code is then transpiled down into a version compatible with all browsers. The most popular transpiler is called [Babel](https://babeljs.io/).

If not using a transpiler, it's a good idea to check browser specs to see what has and hasn't been implemented, or else your code may not work.

# The Spread

The essential parts of ES2015 are included in this section. There are more lessons involving ES2015 featured interweaved into the next few sections, as well as an entirely separate section for the more advanced ES2015+ topics.

Let's get started in the next lesson.

JavaScript added a whole slew of functionality to the language in 2015. These are tools intended to make the language easier, more powerful, and more robust.  We'll go over the most useful of these tools and see how they can truly transform the way we write JavaScript.

Behavior of Functions and Variables

Essential Modern JavaScript - ES2015+ In Depth

Object Oriented Programming: The Core

Object Oriented Programming: `this` and Inheritance

Introduction to Functional Programming

Functional Programming: Arrays and their Powerful Methods

Functional Programming: Objects and their Powerful Methods

A Dive into Asynchronous JavaScript

Advanced Modern JavaScript - Cutting Edge ES2015+

Conclusion

The Future of JavaScript

ES 2015

Changes