Regular Expressions in JavaScript - #1 REGEX ULTRA BASICS

A regular expression (or regex) is way to find strings within strings. It's small code that when applied to a string, will give other strings - either the whole string or parts of the string. This video gives you the ULTRA BASICS of REGEX.

Regexes most common use cases are:
What can we use them for?

1. Validation
If something is formatted correctly. Like verifying if someone has inputted the correct things in a form like an email address or a postal code

2.Extraction
Extract parts of a string that we would like to use. Say find how many times someone wrote "david" in a text.

Replacement
Find all parts of the string with "david" and replace them with something else like "devtips".

You will learn:
- creating regex in two ways in JavaScript: slash notation or with the constructor new RegExp()
- escaping the special characters
- the special characters and how they work: ^, $, *, +, [a-z], [0-9], \w, \d for example

Companion code used in the episode

Or try one of these tools to experiment with regexes. They all do basically the same, it's just a matter of taste:

Read more on MDN, it's the best resource:

[Crimsonaut]

Fantastic idea for a new series. My brother has developed a reputation as being a REGEX master. Developers are always asking his advice with them. They are super useful.

[frederickbogdanoff]

Thank you for this! Really appreciating the new devtips!

[mserrano]

David is getting better and more confident doing these videos :)

[rossgeography]

I have needed this forever - I have the O'Reilly books but never had the motivation to just get started - an intro is much needed - THANKS DevTips Dudes

[MattKander]

Sorry but I found this super confusing, I didn't understand what the special characters meant or why you were using them, opening and starting a string. Would have liked a bit more context as to the structure/grammar of a regex expression.

[joebazooks]

loved it. the most devtips-ish vid u guys have made so far

[Djzaamir]

great video david, looking forward for more videos :)

[BrianDriesenga]

Very nice explanation. I knew someday I would want to add a deeper understanding of RegExp. Glad to hear that this is part of a series. Really want to nail this down. Thanks David!

[gordonsmith]

I needed this in my life so much right now, thank you so much!

[remoteworkboard]

Yo dawg we heard you like backslashes so we escaped your backslashes WITH backslashes.

[bryansharpley]

Great explanation David!
Nice to see this topic covered many explanations of regex are go to stack overflow and get a snippet... there you go regex lol
Thanks for giving a real explanation of the how and why!

[GameOver]

Good job! Even though I'm pretty familiar with regex I'm excited to watch the series :)

[seanrodriguez]

Somehow there's a hole in my heart where Travis use to be :( not you're fault David, it's a great video.

[lucasarregui]

You are Awesome buddy, it can't be explain better... Subscribed !!

[TheBBastard]

Thanks a lot! This was on my checklist to learn for my project! Can't wait for the next episode ;)

[TomLeg]

Used to be, once upon a time, everyone used the regex library from Henry Spencer, of U Toronto. The Perl programming language expanded what regex could do, so nowadays, languages either import the Perl regex library or re-implement it .. or a subset of it.

So it you find regexp powerful, learn Perl and find out what more you can do with regular and not quite regular expressions.

[miguelperezpal]

This is super useful :D thx for sharing your knowledge

[XavierGoncalves]

have been doing form input validation for the past 3 days, even after watching the video and reading about regex, i still hate them

[wingraptor]

I'm fairly new to javascript and was wondering what the ${phoneNumber} is ${isValidNumber} type notation is called. See around 10:37 in the video?

[gunhound]

Any plans of making another series with mpj like the react one?