Learn Regular Expressions (Regex) - Crash Course for Beginners

[@casperdewith]

34:48 For anyone confused why he didn't put a comma after the 2 for “two *or more*” it’s because it is in a lookahead: it only needs to see two digits and then it can stop looking because then we know there are at least two.

[@kevinthomas689]

01:04 Using the Test Method 02:15 Match Literal Strings 02:57 Match a Literal String with Different Possibilities 03:46 Ignore Case While Matching 02:46 Extract Matches 05:33 Find More Than the First Match 07:16 Match Anything with Wildcard Period 08:54 Match Single Character with Multiple Possibilities 10:15 Match Letters of the Alphabet 11:04 Match Numbers and Letters of the Alphabet 12:15 Match Single Characters Not Specified 13:33 Match Characters that Occur One or More Times 14:19 Match Characters that Occur Zero or More Times 15:32 Find Characters with Lazy Matching 18:54 Find One or More Criminals in a Hunt 19:58 Match Beginning String Patterns 20:56 Match Ending String Patterns 21:39 Match All Letters and Numbers 22:47 Match Everything But Letters and Numbers 23:35 Match All Numbers 24:06 Match All Non-Numbers 24:40 Restrict Possible Usernames 27:28 Match White-space 27:56 Match Non-White-space Characters 28:26 Specify Upper and Lower Number of Matches 29:40 Specify Only the Lower Number of Matches 30:10 Specify Exact Number of Matches 30:46 Check for All or None 31:37 Positive and Negative Lookahead.....Check For Mixed Grouping of Characters 35:09 Reuse Patterns Using Capture Group 40:18 Use Capture Groups to Search and Replace 43:17 Remove Whitespace from Start and End

[@JErock25]

Oh, this made me so happy!!! Thanks a lot.

[@kevinthomas689]

@@JErock25 .....😅

[@hattorihanzo5707]

GOD

[@kevinthomas689]

*FOR REFERENCE :----* \f matches form-feed. matches carriage return. matches linefeed. \t matches horizontal tab. \v matches vertical tab. \0 matches NUL character. [\b] matches backspace. \s matches whitespace (short for [\f \t\v\u00A0\u2028\u2029] ). \S matches anything but a whitespace (short for [^\f \t\v\u00A0\u2028\u2029] ). \w matches any alphanumerical character (word characters) including underscore (short for [a-zA-Z0-9_] ). \W matches any non-word characters (short for [^a-zA-Z0-9_] ). \d matches any digit (short for [0-9] ). \D matches any non-digit (short for [^0-9] ). \b matches a word boundary (the position between a word and a space). \B matches a non-word boundary (short for [^\b] ). \cX matches a control character. E.g: \cm matches control-M . \xhh matches the character with two characters of hexadecimal code hh . \uhhhh matches the Unicode character with four characters of hexadecimal code hhhh .

[@nullied]

uhhhh thanks!

[@dj10schannel]

Thank you

[@conaxliu9677]

At 36:36, /(\w+)\s\1/ is actually not the same to /(\w+)\s\(\w+)/ When \1 is used, it enforces the same set of characters, so "regex regex" will match but "regex abcdefg" won't match. (Second word must be the same as the first word.) However, if use /(\w+)\s\(\w+)/ then a string containing any two different words seperated by a space will also match. So the purpose of using \1 is not just to save space.

[@rakeshmali1727]

Exactly!

[@MohammadAlhef]

The Best Course in The World , Thank You From Syria Arab

[@RedEyedJedi]

That was insanely helpful. Thank you so much Beau. I see 8 people don't have complete control over their mouse when clicking the like button.

[@bmoffitt21]

Didn't realize Jerry Seinfeld is getting into the RegEx game. Great course, thank you!!

[@MukeshKumar-rh1rs]

Name 🙏🙏🙏🙏🙏

[@oussama40612]

Hahahahha

[@faraza5161]

Underrated comment

[@Bobson_Dugnutt_Esq]

"What is the deal with regular expressions? Does this imply that there are irregular expressions? Maybe they just need more fiber in their diet."

[@Greerbowski]

Don’t get me started on airline food!

[@OliverWoodphotography]

This has helped me to understand htaccess URL rewrites

[@roeltaga]

27:00 I think you missed something about the case when the username is longer than 2 characters. You made it so it has to start with two letters. I think the right regex would be this : /^[A-Za-z]{2,}\d*$|^[A-Za-z]\d{2,}$/ this checks is the username starts with at least 2 or more letters and then it allows you to have 0 or more numbers at the end. OR also checks if it starts with only one letter but has to have 2 or more numbers for it to be allowed.

[@aditi_bscmathematics_3rdye740]

thank you!!! yeah i was also thinking this and then i read your comment.

[@theCuriousCivilEngineer]

when you use {2,} it means at least two or more alphabets. so there is no problem with that

[@MrBoiks]

spec says numbers aren't allowed if the name is only 2 characters.

[@icaruz9094]

WOOW YOU'RE HIRED!!!

[@julioarruda8182]

@@theCuriousCivilEngineer d88 should pass but it wont

[@Jaybearno]

Step 1- learn regex Step 2- forget regex Step 3- realize you still need to know regex, frantically try combinations on regexr until you get what you need.

[@discodilip2000]

lolol I know this is True because I ended up on this video too

[@JacobKinsley]

I wish there was like, an "expanded" version of regex where instead of symbols and letters, it's words with some aliases for common things. Writing Regex is one of those things I really wish I never have to figure out ever again. Calling the expressions regular is like making a programming language and calling it "better programming language"

[@conaxliu9677]

When I come to Lookaheads at 31:38 it starts to get complicated and confusing. Take the positive lookahead example: let quit = "qu"; let quRegex = /q(?=u)/; quit.match(quRegex); So, quote from 32:29: "It's first going to check for the 'q', and it's going to look ahead to make sure there is an 'u' LATER in the string." If that statement is correct then I would expect the following also works: let quit = "quit fooling around"; let quRegex = /q(?=fool)/; quit.match(quRegex); I expected it to work because I am taking "later in the string" as anything between the 'q' and the end of the string. So if the string is "quit fooling around" then I expect /q(?=fool)/ will also match. However, this is not the case. The lookahead actually just check the pattern NEXT to the 'q'. So only these would match: /q(?=u)/; /q(?=uit)/; /q(?=[a-zA-z ]*fool)/; Does that make sense or have I misunderstood something?

[@mariocardenas1259]

Yes that's right, in order to do what you want to do you would have to use /q(?=.*fool)/

[@VeedFeed]

the best guide for regex!!!!!!!!!!!!!!!!!!!

[@anyavailablehandle]

Great clear and concise teaching. Great video . Thanks

[@HostDotPromo]

If regex was easy, I wouldnt be watching this 🔥 hard to remember how it works.

[@nkplus]

Thanks Beau !! ---- Finally got !! which I was desperately waiting for ...

[@conaxliu9677]

All my life I felt like something was missing, until I found you.

[@127.]

Corona, Corona... Be my Corona...

[@yasam9311]

This video is soo great. gives everything concisely. sincerely thank you!

[@faronildomelancia2454]

I'm brasilian and i love your channel.Congratulations!!

[@ahmedhamed8324]

Man!! they've must read my mind!

[@TheSclare]

Finally someone is talking about this topic

[@TechnoDB]

freeCodeCamp explanation is dope.. 😊

[@PabloNevares]

I think there's an error in the video explaining capture groups. At 36:36 the author says that this: /(\w+)\s\1/ and this: /(\w+)\s(\w+)/ Would have been the same thing, just shorter due to using \1 to refer to the previous capture group. These are not the same regex patterns. The first example will test whether the second string is a repeat of the first. The second example will allow two different strings to pass the test. Try both with "regex regex" and "regex rerex" to see the difference.

[@pnuematikon]

I noticed this too. Figured I'd see if there were any other comments before posting.

[@conaxliu9677]

Ha, I just commented on that, and then started to read other people's comments...

[@ricardocambundo2527]

This is a really good tutorial Got a deeper understanding of RegExp

[@danhle7999]

thank you for the explaination this is exactly what i am looking for

[@rockybalboa1086]

Very detailed and we'll put together!

[@hammadurrehman3850]

Well explained best video one can get on regex.

[@gurunathrao2985]

Regex is the criminal !

[@pupfriend]

Little known fact. The guy who invented regex also invented water boarding

[@LurajerLP]

For real??😂

[@nicknamekenny]

Source?

[@arnoldp8962]

Meh, water boarding has been around since the catholic inquisition or earlier

[@arunteltia7888]

what is water boarding

[@noelkirkland]

Haha, one guy says "source?" haha. I think what OP was saying is that learning regex is like torture.

[@Bruno-ds8ze]

yeah!! i was waiting for this, thanyou very much

[@JohnBartmannMusic]

35:00 "This is going to match for 5 or more characters". Noob question: doesn't the {5} mean it's going to match EXACTLY 5 characters?

[@Z-713]

Yes! It does. {x,y} the x is the minimum, and the y is the maximum. {1,3} will match 1, 2, or 3. {5,} will match 5 OR MORE. {5} will match 5 EXACTLY. So, when the maximum is left blank ({x,}) it treats it as x OR MORE, and when the minimum and maximum don't exist ({x}) it treats it as x EXACTLY.

[@JohnBartmannMusic]

​@@Z-713 He says "this is going to match 5 or more characters" but the code will match exactly 5. The code reads {5} but his voiceover suggests that the code reads {5,}. Is there a mistake or am I missing something?

[@Z-713]

@@JohnBartmannMusic Yes, you are correct. He did make a mistake in the video.

[@theCuriousCivilEngineer]

@@JohnBartmannMusic it's because he is using it in a look ahead which means it will look through exactly "five" characters and is the code finds five character it will not care about the rest of the string.

[@JohnBartmannMusic]

@@theCuriousCivilEngineer thank you

[@JuanSB827]

I think at 36:40 there is mistake. He says that replacing \1 is just to avoid rewriting (\w+) However /(\w+)\s\1/ tests TRUE for "regex regex" but FALSE or "regex somethingelse" /(\w+)\s(\w+)/ tests TRUE for "regex regex" but TRUE for "regex somethingelse"

[@dj10schannel]

Man this was pretty darn good thanks beau 🙏

[@Ali-vz9rs]

And another super useful video. Thank You freeCodeCamp.

[@kefas404]

thank you this was really helpful to get the basics

[@rolandoriley]

Excelent course. .. thanks!

[@mrzack184]

million thanks for this awesome video! it really taught me a lot.

[@swapnilyadav714]

You guys are using Seinfeld vision from 30 Rock😁

[@dhruva167]

Thanks for Great tutorial.

[@abdullahfurkanozbek7558]

I really consalidate my regex knowledge, thank you 😊

[@WickedTwitches]

Be me, find a video, Beau is the narrator, leave understanding everything about rejects

[@norflit]

the solution at 34:58 is not correct and the original challenge throws an error if I use 5 instead of 6 when testing string '12345'. let me know if this is a misunderstanding 🙂

[@LevisRaju]

I think they improved the test cases now. Coz I got the same error

[@rajeshsahu3073]

For the username pattern challenge, I think you have missed the last point that says If there are only two letters then there should not be any number ?

[@ntintelomazibuko9722]

He specified at least 2 letters so it will work

[@jachiu89]

@@ntintelomazibuko9722 it's actually not working, I put the code he used and it's not passing because the regex won't match "Z97" since he used the {2,0} it needs at least the first two characters to be letters, it won't allow numbers.

[@shankerm3959]

I was looking out for that as well.

[@roeltaga]

@@ntintelomazibuko9722 He made it so it has to start with 2 letters. But actually if the username is going to be longer than 2 characters needs to allow the 2nd one to be a number. I think the right regex would be /^[A-Za-z]{2,}\d*$|^[A-Za-z]\d{2,}$/

[@ashutoshlohogaonkar8348]

@@roeltaga Thanks man.. I was unable to pass one case of"Z97"

[@chrikrah]

37:03 I don't think that /(\w+)\s\1/ is the same as /(\w+)\s(\w+)/ The former matches the exact same word again. So it would match "apple apple" but not "apple kiwi". Whereas the latter would match both "apple apple" and "apple kiwi". Correct me if I'm wrong.

[@Martin-delta]

I was thinking the exact same thing. I think you are correct.

[@cataxcab]

Is regex the same in Java?

[@chrikrah]

@@cataxcab Unfortunately, there is no standard for regular expressions. There are a lot of overlaps and the basics are the same, but a lot of details differ. Checkout www.regular-expressions.info - it has a lot of information on the different flavors of Regex.

[@fabrice9848]

@22:00 He confused slash with backslash, frequent mistake.

[@AbhishekKumar-mq1tt]

Thank u for this awesome video

[@katieneko674]

how many times am I going to forget everything and come back to learn it again? Step by step is simple. putting it together is hard, and remembering what random letters do is simply not going to happen. Anyone got a way to memorize this or am I SOL?

[@thuglife896]

Helpful as always Beau.

[@bilalbeny4172]

thank u so much. it was an useful course.

[@Blentux]

When I first got to do with Regex I hated it. Now that I begin to understand it, I'm kinda starting having fun lol

[@shashishekhar----]

Thank you Beau , much appreciated thing !

[@r1shabhnegi]

Thanks a lot Beau!

[@qlevrqt8886]

in 18:36 I don't understand why the result wouldn't only be [""], why doesn't it stop once it sees the second bracket? Because technically "h1" is inside .

[@rjse4905]

Awesome explained. Thanks sir

[@johnsonjayaraj7209]

Great video, thanks!!

[@kostiantynkarzhanov9216]

Beau, Thank you very much for this tutorial! It is great!

[@germanduterte7110]

Regular Expression is the most hardest part of all. It's easy to forget the rules and difficult to learn.

[@jeneshnapit3248]

What a coincidence I just got to regex like 10 mins ago. DM me if anyone looking to work on projects together.

[@bafana_mhlamvu]

What level of coding knowledge are those projects catering for?

[@jeneshnapit3248]

@@bafana_mhlamvu I'd say begginner started learning JS a month ago know the basics and stuff but following the FCC JS at the moment. Can do DOM manipulation and have made a simple todo list.

[@bafana_mhlamvu]

​@@jeneshnapit3248​Although relearning JavaScript, that sums my current level of the language... I'm interested in doing these projects...

[@sandoxs]

First of all sorry my bad english...Wonderfull tutorial...just to mention...There's an error on 27:22 : about username restrictions...in the conditions it was mentioned that 2 letter usernames cannot have numbers after letters but actually it can...pls fix it

[@conaxliu9677]

I don't see the issue you described. What user name did you provide?

[@rakibhossensarkar6080]

mindblowing

[@darkriderofwest]

Very educational. Thanks a lot.

[@johnlewis7736]

Excellent. Thanks!

[@VictorShirima-y2p]

thank you its a good tutorial

[@jvlensez]

Hi Beau, 1. Which program are you using for the code in the video? 2. I really liked the mouse pointer, could you please share how I could get that on my PC?

[@Webnoob]

Excellent tutorial. Thx.

[@LHSgoatman]

Thanks for the video, but I think you are mistaken or misspoke on the reuse pattern using capture group. You stated that if you replace the \1 with the same capture pattern that it would be the same thing. I believe that is a mistake, for example use repeatstring. If you replaced the \1 with (\w+) then Yes it would match the string, but it would also match “regex testing” and I don’t think that is what you are trying to do.

[@tonydanza4502]

I guess specifying number of matches inside a look ahead uses different syntax than specifying number of matches not inside a look ahead? outside a look ahead {5} means exactly 5 but inside it means at minimum I take it?

[@Noritoshi-r8m]

Great lecture, ty.

[@darkcodelab]

Waiting for this!!!!!!

[@MatheusPereira-nn9dj]

when we have this regexp information stored in variables , and from what I understand in the console they are in an array, can I use map() or filter() syntax?

[@ajeetyadav4044]

Thanks Beau;

[@arthurserafim8066]

Just got busted in a code test, so here am I!

[@dr_morpho]

Thank you!))

[@mikiaszerihun3681]

I think something went wrong on username validator regex. what do you think Mr Beau Carnes.

[@emanuelmaza718]

En la parte de restricción de usuarios 24:40 solo me deja pasar el test utilizando la expresión /^[A-Za-z]{2,}\d*$ |^[A-Za-z]{1,}\d{2,}$/ si alguien encontró otra solución me la podría escribir en comentarios. At Restrict Possible Usernames 24:40 I'm able to pass the test with the expression /^[A-Za-z]{2,}\d*$ |^[A-Za-z]{1,}\d{2,}$/ Plz if there's any other solution can you write it in the comments.

[@felixnoel8844]

This is certainly an informative video however it is not a beginner's video due to how fast paced it is and the assumption that some prerequisite knowledge is present. In this case JavaScript. Nonetheless it is a good tutorial for people who want to refresh their knowledge on this particular area.

[@Ddjfhfjfj]

10:07 Why aeiou in bracket don’t need comma ？

[@whateveritwasitis]

Wanted to thank you i hit this in class, lmao but I did it with my collar😂😂😂i knew something was wrong, still got it though

[@LurajerLP]

Thank You 🤩

[@leeboss373]

Why does I mean capitals and non capital? Why does g mean flag all? And how do you know this?

[@kzakaria91]

it's a standard thingy big boi, all programming languages has some kind of regular expression

[@freecodecamp]

"g" stands for global match, "i" stands for ignore case

[@leeboss373]

freeCodeCamp.org thanks👍🏻

[@ttbtv6266]

39:18 bruh what. Why would it match the space after the third '42' when the last element is any digits?

[@souravsuman1993]

5:28 what will happen if their is multiple match in a single line? Will it return array of matching strings?

[@redps8611]

i think just the first unless g is specified at the end of the regex..... right?

[@conaxliu9677]

@@redps8611 Right.

[@emanuelmaza718]

En la parte de restricción de usuarios 24:40 solo me deja pasar el test utilizando la expresión /^[A-Za-z]{2,}\d*$ |^[A-Za-z]{1,}\d{2,}$/ si alguien encontró otra solución me la podría escribir en comentarios. At Restrict Possible Usernames 24:40 I'm able to pass the test with the expression /^[A-Za-z]{2,}\d*$ |^[A-Za-z]{1,}\d{2,}$/ Plz if there's any other solution can you write it in the comments.

[@deepakbhargav7434]

THANK YOU BOSS

[@GemsofPakistan1]

How to Find a regular expression that matches the last two columns of the file. ?

[@СергейКрица]

35:07 regex doesn't work in case of less than 5 chars console.log(/(?=\w{5})(?=\D*\d{2})/.test("ast99")) and returns true.

[@rakibhossensarkar6080]

awesome

[@ttbtv6266]

At 43:22, why doesn't /^(\s+)\1$/.test(' Hello, World! ') equal True? Can someone explain this to me pls?

[@abdoemad6938]

perfect !

[@holo6433]

Last task you can do without replace /[^\s].+[^\s]/

[@harwinderthakur9708]

Thanks

[@ankitmehrotra8519]

Beau ur name is sweet and so is ur way of explaining everything..Many thanks beau, ur awesome..😁😁👏👏🍻🍻

[@younglonny2220]

Beau is beautiful in french (masculine, belle is feminine)

[@prashantsuryawanshi9930]

Can you tell me , which code editor are you using?

[@freecodecamp]

scrimba.com

[@thesavagesalmon9464]

use vscode

[@orashusedmund7675]

in the username example you gave, how would we restrict Two-letter usernames from having numbers /^[A-Za-z]{2,}\d*$/ doesn't enforce this restriction

[@GemsofPakistan1]

How to Find a regular expression that matches the last two columns of the file. ? PLEASE HELP

[@charlesludwig8672]

Next, Adam Sandler should narrate functional programming

[@rajeshprasadh3717]

Sir do you have any course which can teach me about how to make dynamic graph using JavaScript I want to make one project for my college. In that I will compare 10 wealthiest people in the world between 1990 to 2019 Also we need to fetch data from another website for this project. Please help and reply

[@freecodecamp]

Look into D3: kzbin.info/www/bejne/eWXXZ6Scfb9pitk

[@AbdoMohamed-ml7ei]

at Restrict Possible Usernames 24:40 if the string is three characters (one letter and two numbers ) it will get false so the expression should be /^[A-Za-z]{2,}\d*$ |^[A-Za-z]{1,}\d{2,}$/ (WRONG ANSWER Check Kristof S comment)

[@AbdoMohamed-ml7ei]

yeah the two characters long spec i missed that. thank you

[@cataxcab]

Hey, will I be able to use this in Java? I googled, it says lookbehind isn't supported in js, or something like that!

[@XilvermistTrollawney]

33:50 I'm lost....

[@seriousthing240]

Sir tell me webmethod

[@viniciusra9584]

Why not use comma instead of using let multiple times? instead of : let a = 0 let b = 1 let c = 2 let d = 3 use this: let a = 0, b = 1, c = 2, d = 3;

[@OnyxBloodStone]

It's not gonna fit in a single line. Think about mobile viewers