Learn Regular Expressions

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Course level: Intermediate

This tutorial teaches you regex in JavaScript through 34 screencasts. It explains regular expressions step-by-step from basic to advanced so that you don't fall off along the way. This ensures that you finally learn regex once and for all.

What's inside

This course contains 35 interactive screencasts

Learn Regular Expressions

35 lessons 46 min

1. Regular Expressions Intro

2. Using the Test Method

3. Frontend Career Path

4. Match Literal Strings

5. Match a Literal String with Different Possibilities

6. Ignore Case While Matching

7. Extract Matches

8. Find More Than the First Match

9. Match Anything with Wildcard Period

10. Match Single Character with Multiple Possibilities

11. Match Letters of the Alphabet

12. Match Numbers and Letters of the Alphabet

13. Match Characters that Occur One or More Times

14. Match Characters that Occur One or More Times

15. Match Characters that Occur Zero or More Times

16. Find Characters with Lazy Matching

17. Find One or More Criminals in a Hunt

18. Match Beginning String Patterns

19. Match Ending String Patterns

20. Match All Letters and Numbers

21. Match Everything But Letters and Numbers

22. Match All Numbers

23. Match All Non-Numbers

24. Restrict Possible Usernames

25. Match Whitespace

26. Match Non-Whitespace Characters

27. Specify Upper and Lower Number of Matches

28. Specify Only the Lower Number of Matches

29. Specify Exact Number of Matches

30. Check for All or None

31. Positive and Negative Lookahead

32. Reuse Patterns Using Capture Groups

33. Use Capture Groups to Search and Replace

34. Remove Whitespace from Start and End

35. Regular Expressions Outro

You'll learn

Regex basics

Test matches

Literal strings

Case insensitive

Single character

Match letters

Match numbers

Single match

Multiple matches

Wildcards

Lazy matching

Begins with match

Ends with match

Inclusive match

Exclusive match

Whitespace match

Lookahead

Capture groups

Prerequisites

Before taking this course, you should have a basic understanding of JavaScript. Here’s our suggested resource to get you up to speed.

Learn JavaScript

207 lessons | 10 hours 23 min

with Per Harald Borgen

Per Harald Borgen

Meet your teacher

The course creator

freeCodeCamp

freeCodeCamp is a community that helps you learn to code, then get experience by contributing to open source projects used by nonprofits. Their Scrimba sceencasts are recorded by their brilliant instructor Beau Carnes and are based on their core curriculum.

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Why this course rocks

This course features freeCodeCamp's Regular Expressions curriculum recorded as Scrimba screencasts. It introduces you to regular expressions (also called regex or regexp) through the lens of JavaScript. And as this is a Scrimba course, you'll be able to experiment with the expressions whenever you want. This is crucial when learning regex, as there are a lot of details to remember. Interacting with the code makes the knowledge stick, as opposed to simply watching normal video tutorials.

About freeCodeCamp

The lectures are recorded by Beau Carnes. Beau is the man behind some of the most popular courses at freeCodeCamp's YouTube channel, so you'll be in good hands. He explains concepts clearly and thoroughly, but without wasting your time.

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F to the A oracle

to the Q

What is regex used for?

Regex is short for regular expression, a regex is a string of text which you can use to create patterns that help match, locate, and manage text.

How does regex work?

Almost all modern regex flavours are based on regex-directed engines. If a match is found, the engine advances through the regex and the subject string. If a token fails to match, the engine backtracks to a previous position in the regex and the subject string where it can try a different path through the regex.

Are regular expressions important?

Regular expressions are a very terse way to express how to match patterns in text. The requirement to parse and extract data from text or to validate that some text conforms to a specific pattern comes up very often in programming. It is important to learn about regex and at least know what to google when you encounter one or need to use it.