Explore JavaScript regular expressions: learn about regex history, create patterns with special characters, parse data, and match passwords/emails, gaining comprehensive text processing skills.

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Regular Expressions, also known as Regex, come in handy in a multitude of text processing scenarios. Regex defines a search pattern using symbols and allows you to find matches within strings. The applications of this span from software engineering to data science and beyond.

In this course, you will begin with an introduction to regex, its history, and various types of regular expressions. 

You will then learn how to create your own regular expressions using various techniques and special characters. In the latter half of the course, you will explore RegExp Objects, how to parse data, turn phrases into an array of strings, and lastly password and email pattern matching.

By the end of this course, you will be a regular expressions expert.

JavaScript Regular Expressions in Detail

# Introduction 

Groups are an incredibly useful part of regular expressions because they allow you to grab a portion of the matching pattern and use it in your code logic or reference it while doing a string replacement.


The groups you can grab and reference later are called *capturing groups*, which, as the name suggests, means you’re able to capture them and use them however you want. 
On the other hand, you have *non-capturing groups,* which allow you to organize your matched expressions without the added benefit of having individual access to them for further operations. Take a look at the example down below to learn how these can be useful.


# _Capturing_ the hostname of a URL
Let’s pretend you need to *capture* the hostname of a URL from a particular string. In fact, let’s use the following URLs as examples:

- https://www.fdoglio.com/blog
- ftp://google.com
- http://www.yahoo.com

> When trying to create a regular expression, it’s always useful to use several variations of a string to test your results rather than using a single string. This is because you’re creating a pattern that should be able to match (and in this case capture) several variations and not just a single string.



Notice how we have three different URLs with different protocols, different hostnames (including the optional *www*), and different URIs. That’s the kind of variation you want when creating your list of testing strings.

So, what we want to do is ensure we’re matching something that starts with a protocol section, followed by the hostname and potentially has a URI.

Let's learn about capturing and non-capturing groups with the help of an example.


The Beginning of Regular Expressions

The Anatomy of Regular Expressions

The RegExp Object

Thinking in Regular Expressions

Regular Expressions in the Wild

Wrapping Up

Special Characters: Capturing and Non-Capturing Groups

Introduction