Understanding JavaScript RegExp

Learn JavaScript Regular Expressions step-by-step from beginner to advanced levels with hundreds of examples and exercises. Visit https://youtu.be/8X-hUel3GxM for a short video about the book.

The book also includes exercises to test your understanding, which are presented together as a single file in this repo — Exercises.md.

For solutions to the exercises, see Exercise_solutions.md.

See Version_changes.md to keep track of changes made to the book.

E-book

• You can purchase the pdf/epub versions of the book using these links:
  • https://learnbyexample.gumroad.com/l/js_regexp
  • https://leanpub.com/js_regexp
• You can also get the book as part of these bundles:
  • All books bundle bundle from https://learnbyexample.gumroad.com/l/all-books
    • Includes all my programming books
  • Awesome Regex bundle from https://learnbyexample.gumroad.com/l/regex or https://leanpub.com/b/regex
• See https://learnbyexample.github.io/books/ for a list of other books

For a preview of the book, see sample chapters.

The book can also be viewed as a single markdown file in this repo. See my blogpost on generating pdfs from markdown using pandoc if you are interested in the ebook creation process.

For the web version of the book, visit https://learnbyexample.github.io/learn_js_regexp/

Testimonials

Literally was having a mini-breakdown about not understanding Regex in algorithm solutions the other day and now I'm feeling so much better, so thank YOU! I genuinely feel like I'm developing the skill for spotting when and where to use them after so much practice!

— feedback on twitter

Feedback

⚠️ ⚠️ Please DO NOT submit pull requests. Main reason being any modification requires changes in multiple places.

I would highly appreciate it if you'd let me know how you felt about this book. It could be anything from a simple thank you, pointing out a typo, mistakes in code snippets, which aspects of the book worked for you (or didn't!) and so on. Reader feedback is essential and especially so for self-published authors.

You can reach me via:

• Issue Manager: https://github.com/learnbyexample/learn_js_regexp/issues
• E-mail: echo 'bGVhcm5ieWV4YW1wbGUubmV0QGdtYWlsLmNvbQo=' | base64 --decode
• Twitter: https://twitter.com/learn_byexample

Table of Contents

1. Preface
2. Why is it needed?
3. RegExp introduction
4. Anchors
5. Alternation and Grouping
6. Escaping metacharacters
7. Dot metacharacter and Quantifiers
8. Interlude: Tools for debugging and visualization
9. Working with matched portions
10. Character class
11. Groupings and backreferences
12. Interlude: Common tasks
13. Lookarounds
14. Unicode
15. Further Reading

Acknowledgements

• MDN: Regular Expressions — documentation and examples
• /r/learnjavascript/ and /r/regex/ — helpful forums for beginners and experienced programmers alike
• stackoverflow — for getting answers to pertinent questions on JavaScript and regular expressions
• tex.stackexchange — for help on pandoc and tex related questions
• canva — cover image
• Warning and Info icons by Amada44 under public domain
• oxipng, pngquant and svgcleaner — optimizing images
• mdBook — for web version of the book
  • mdBook-pagetoc — for adding table of contents for each chapter
  • minify-html — for minifying html files

License

The book is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

The code snippets are licensed under MIT, see LICENSE file.