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

Looking at our code, we can easily find the pattern. Variable names have one of the following characters next to them: a blank space, a dot, a closing parenthesis, or a semicolon. This is true for our example code, but we could make this a bit more generic by extending that definition if we had to.

# Regular expression 

By adding that condition, we can use a conditional match, also known as a *positive lookahead* (if you don’t remember what that is, go back to [chapter 2](https://www.educative.io/courses/javascript-regular-expressions-in-detail/special-characters-quantifiers), and once you’re done, get back here). But to make the lookahead work, we need to stop matching only the lowercase and uppercase letters and start capturing the different sections of the word so we can be sure to 
ignore words that aren’t followed by one of our characters.


>Notice how this example is assuming our camel case variables are only formed by two words. We’ll leave it as an exercise for you to expand the following expression to work for longer words.

And here is the final result:

```js
(\[a-z]+)([A-Z\][a-z]*)(?=[ |\)|\.|;])
```

The first group captures the lowercase half of the word, while the second group captures the second half as long as it’s followed by one of our predefined characters.


# Verification with JS code

And, with it, if we use the same text editor with the JavaScript code from above:




Now let's write the regular expression for the problem discussed in the previous lesson and verify it using JS code. 

The Beginning of Regular Expressions

The Anatomy of Regular Expressions

The RegExp Object

Thinking in Regular Expressions

Regular Expressions in the Wild

Wrapping Up

Capturing Variable Names Alone