Regex Tutorial | Regular Expressions Explained

In this tutorial, we will look at Regex (Regular Expressions) basics and some examples of useful regex patterns. Regex is used to describe and select patterns inside of string data. Regular Expressions make up a small language that may be utilized inside of many other programming languages. Regex patterns may be used inside of JavaScript, Python, Java, C++, and more.

✅ Quick Concepts outline:
Regex Basics:
• Character sets
• Negated sets
• Ranges
• Global and Case Insensitive flags
• Special character: dot
• Escaping special characters
• Word characters
• Digits
• Whitespace
• Match all characters
• Match the beginning of a string
• Match the end of a string
• Multiline flag
• Capturing and Non-capturing groups
• Positive and Negative lookahead
• Quantifiers
• Select one or more
• Select zero or more
• Make a selection optional
• Make a quantifier lazy instead of greedy
• Alternation: using "or" |
• Example pattern 1
• Example pattern 2
• Example pattern 3

📚 References:

📺 More Beginner JS Videos:

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#regex #regular #expressions

[wozza]

By FAR the best introductory tutorial to regular expressions that I've been able to find. Thanks a bunch, Dave.

[ahmad-murery]

Very well explained,
It took me a lot of time to get the basics in the past because of the lacking of good practical examples like these.
Regards

[sweeball]

Clear and concise short tutorial. Thanks Dave; just what was need for an intro to Regex.

[yatin]

This was quite enlightening and fun to explore!

[mattwaala]

The Great thing about your tutorials is that, you follow along the lines of documentations

[mostafahusany]

Thanks again and again for all your hard work <3

[kostiantynkarzhanov]

Hey Dave, I just wanted to say a big thank you! Your tutorial was awesome, as always!💛

[ogundekoadegbenga]

Why am I just seeing your channel? Came here through twitter. Damn! I was always scared of regex and now I feel a bit more confident. Codewars, I am coming for ya. Thanks a lot David

[Grihlo]

That was clear and straight forward - thank you so much!
I'm still a bit anxious after the previous lesson which I didn't get completely and I thought that the next is going to be even more complicated but fortunately I was wrong :)

[vladislavamarkova]

Great explanation of regex, very useful! And, nice choice of example string :) Neil Young`s Heart of Gold is an awesome song, thank you!

[sagars]

Cool man..it's impressive...
Smart learning..

[samhatake]

what is the time complexity of evaluation of regex dave ? If i were to do with only js code this will vary according to expression i want it could range from quadratic to even more depending upon what i am trying to get out from string

[saquibansari]

Hello Dave sir, first of thank you so much that im being confident in JS just because of you...❤❤❤

My question is, are these all for beginners?? How can get intermediate or advanced topic...???

Please do reply...

[mahioocode]

Overall ok. But Struggling to understand the backreferences concept used with groups. Any content/resource on that?

[Vikram]

can you please share real world scenarios where regex needs to be used ?

[sagars]

String version="Version 91.0.864.59: June 24";
Buddy how to fetch only 91.0.864.59 from above string using regex??
I have done it using this "\\d\\d\\.\\d\\.\\d+\\.\\d+" but I believe this is not good approach.Can you please help me out.
Cheers