Develop Reference

Regex for bible references

I am working on some code for an online bible. I need to identify when references are written out. I have looked all through stackoverflow and tried various regex examples but they all seem to fail with single books (eg Jude) as they require a number to proceed the book name. Here is my solution so far :
/((?:(I+|1st|2nd|3rd|First|Second|Third|1|2|3))?( )?(Gen|Ge|Gn|Exo|Ex|Exod|Lev|Le|Lv|Num|Nu|Nm|Nb|Deut|Dt|Josh|Jos|Jsh|Judg|Jdg|Jg|Jdgs|Rth|Ru|Sam|Samuel|Kings|Kgs|Kin|Chron|Chronicles|Ezra|Ezr|Neh|Ne|Esth|Es|Job|Job|Jb|Pslm|Ps|Psalms|Psa|Psm|Pss|Prov|Pr|Prv|Eccles|Ec|Song|So|Canticles|Song of Songs|SOS|Isa|Is|Jer|Je|Jr|Lam|La|Ezek|Eze|Ezk|Dan|Da|Dn|Hos|Ho|Joel|Joe|Jl|Amos|Am|Obad|Ob|Jnh|Jon|Micah|Mic|Nah|Na|Hab|Zeph|Zep|Zp|Haggai|Hag|Hg|Zech|Zec|Zc|Mal|Mal|Ml|Matt|Mt|Mrk|Mk|Mr|Luk|Lk|John|Jn|Jhn|Acts|Ac|Rom|Ro|Rm|Co|Cor|Corinthians|Gal|Ga|Ephes|Eph|Phil|Php|Col|Col|Th|Thes|Thess|Thessalonians|Ti|Tim|Timothy|Titus|Tit|Philem|Phm|Hebrews|Heb|James|Jas|Jm|Pe|Pet|Pt|Peter|Jn|Jo|Joh|Jhn|John|Jude|Jud|Rev|The Revelation|Genesis|Exodus|Leviticus|Numbers|Deuteronomy|Joshua|Judges|Ruth|Samuel|Kings|Chronicles|Ezra|Nehemiah|Esther|Job|Psalms|Psalm|Proverbs|Ecclesiastes|Song of Solomon|Isaiah|Jeremiah|Lamentations|Ezekiel|Daniel|Hosea|Joel|Amos|Obadiah|Jonah|Micah|Nahum|Habakkuk|Zephaniah|Haggai|Zechariah|Malachi|Matthew|Mark|Luke|John|Acts|Romans|Corinthians|Galatians|Ephesians|Philippians|Colossians|Thessalonians|Timothy|Titus|Philemon|Hebrews|James|Peter|John|Jude|Revelation))(([ .)\n|])([^a-zA-Z]))([\d])?([:\d])?([:\d])?/gi;
Here is the regex code with some sample text to match:
https://regexr.com/5pfg3
On the above you will notice, Jude if double spaced will work. If I put a full stop after it will work. I know the issue is this section :
(([ .)\n|])([^a-zA-Z]))
What I want is to match spaces, brackets, new lines BUT not a letter.

It does not match as it expects 2 characters using (([ .)\n|])([^a-zA-Z])) where the second one can not be a char a-zA-Z due to the negated character class, so it can not match the s in Jude some.
What you might do is make the character class in the second part optional, if you intent to keep all the capture groups.
You could also add word boundaries \b to make the pattern a bit more performant as it is right now.
See a regex demo
(Note that Jude is listed twice in the alternation)
If you only want to use 3 groups, you can write the first part as:
\b(?:(I+|1st|2nd|3rd|First|Second|Third|[123]) )?
The second part will be the alternation with the names, and in the 3rd part you can match one of the character class followed by the digit part and make that optional as a whole (so you don't match a trailing space or char after the word without the digits).
(?:[ .)\n|](\d+(?::\d+){0,2}\b))?
The full pattern will look like
\b(?:(I+|1st|2nd|3rd|First|Second|Third|[123]) )?(Gen|Ge|Gn|Exo|Ex|Exod|Lev|Le|Lv|Num|Nu|Nm|Nb|Deut|Dt|Josh|Jos|Jsh|Judg|Jdg|Jg|Jdgs|Rth|Ru|Sam|Samuel|Kings|Kgs|Kin|Chron|Chronicles|Ezra|Ezr|Neh|Ne|Esth|Es|Job|Job|Jb|Pslm|Ps|Psalms|Psa|Psm|Pss|Prov|Pr|Prv|Eccles|Ec|Song|So|Canticles|Song of Songs|SOS|Isa|Is|Jer|Je|Jr|Lam|La|Ezek|Eze|Ezk|Dan|Da|Dn|Hos|Ho|Joel|Joe|Jl|Amos|Am|Obad|Ob|Jnh|Jon|Micah|Mic|Nah|Na|Hab|Zeph|Zep|Zp|Haggai|Hag|Hg|Zech|Zec|Zc|Mal|Mal|Ml|Matt|Mt|Mrk|Mk|Mr|Luk|Lk|John|Jn|Jhn|Acts|Ac|Rom|Ro|Rm|Co|Cor|Corinthians|Gal|Ga|Ephes|Eph|Phil|Php|Col|Col|Th|Thes|Thess|Thessalonians|Ti|Tim|Timothy|Titus|Tit|Philem|Phm|Hebrews|Heb|James|Jas|Jm|Pe|Pet|Pt|Peter|Jn|Jo|Joh|Jhn|John|Jude|Jud|Rev|The Revelation|Genesis|Exodus|Leviticus|Numbers|Deuteronomy|Joshua|Judges|Ruth|Samuel|Kings|Chronicles|Ezra|Nehemiah|Esther|Job|Psalms|Psalm|Proverbs|Ecclesiastes|Song of Solomon|Isaiah|Jeremiah|Lamentations|Ezekiel|Daniel|Hosea|Joel|Amos|Obadiah|Jonah|Micah|Nahum|Habakkuk|Zephaniah|Haggai|Zechariah|Malachi|Matthew|Mark|Luke|John|Acts|Romans|Corinthians|Galatians|Ephesians|Philippians|Colossians|Thessalonians|Timothy|Titus|Philemon|Hebrews|James|Peter|John|Revelation)\b(?:[ .)\n|](\d+(?::\d+){0,2}\b))?
Regex demo of the full pattern

Need help to find the right regex pattern to match

my RegEx is not working the way i think, it should.
[^a-zA-Z](\d+-)?OSM\d*(?![a-zA-Z])
I will use this regex in a javascript, to check if a string match with it.
Should match:
12345612-OSM34
12-OSM34
OSM56
7-OSM
OSM
Should not match:
-OSM
a-OSM
rOSMann
rOSMa
asdrOSMa
rOSM89
01-OSMann
OSMond
23OSM
45OSM678
One line, represents a string in my javascript.
https://www.regex101.com/r/xQ0zG1/3
The rules for matching:
match OSM if it stands alone
optional match if line starts with digit/s AND is followed by a -
optional match if line ends with digit/s
match all 3 above combined
no match if line starts with a character/word except OSM
no match if line end with chracter/word except OSM
I Hope someone can help.

You can use the following simplified pattern using anchors:
^(?:\d+-)?OSM\d*$
The flags needed (if matching multi-line paragraph) would be: g for global match and m for multi-line match, so that ^ and $ match the begin/end of each line.
EDIT
Changed the (\d+-) match to (?:\d+-) so that it doesn't group.

[^a-zA-Z](\d+-)?OSM\d*(?![a-zA-Z])
[^a-zA-Z] In regex, you specify what you want, not what you don't want. This piece of code says there must be one character that isn't a letter. I believe what you wanted to say is to match the start of a line. You don't need to specify that there's no letter, you're about to specify what there will be on the line anyway. The start of a regex is represented with ^ (outside of brackets). You'll have to use the m flag to make the regex multi-line.
(\d+-)? means one or more digits followed by a - character. The ? means this whole block isn't required. If you don't want foreign digits, you might want to use [0-9] instead, but it's not as important. This part of the code, you got right. However, if you don't need capture blocks, you could write (?:) instead of ().
\d*(?![a-zA-Z]) uses lookahead, but you almost never need to do that. Again, specifying what you don't want is a bad idea because then I could write OSMé and it would match because you didn't specify that é is forbidden. It's much simpler to specify what is allowed. In your case since you want to match line ends. So instead, you can write \d*$ which means zero or more digits followed by the end of the line.
/^(?:\d+-)?OSM\d*$/gm is the final result.

Regular expression - val.replace(/^[^a-zA-Z0-9]*|[^a-zA-Z0-9]*$/g,"'');

I was learning regular expression, It seems very much confusing to me for now.
val.replace(/^[^a-zA-Z0-9]*|[^a-zA-Z0-9]*$/g, '');
In the above expression
1) which part denotes not to include white space? as i am trying to exclude all non alphanumeric characters.
2) Since i don't want to use even '$' and ''(underscore) can i specify '$' & ''(underscore) in expression something like below?
val.replace(/^[^a-zA-Z0-9$_]*|[^a-zA-Z0-9$_]*/g, '');?
3) As 'x|y' specify that - "Find any of the alternatives specified". Then Why we have used something like this [^a-zA-Z0-9]|[^a-zA-Z0-9] which is same on both sides?
Please help me understand this, Finding it bit confused and difficult.

This regular expression replaces all starting and trailing non alphanumeric characters from the string.
It doesn't specifically specifies whitespace. It just negates every thing other than alphanumeric characters. Whatever inside square bracket is a character set - [Whatever]. A starting cap(^) INSIDE the character set says its a negation. So [^a-zA-Z0-9]* says zero or more characters which are other than a-z, A-z or 0-9.
The $ sign at the end says, to the end of string and nothing to do with $ and _ symbols. That will be already included in the character set as it all non alpha numeric characters.
Refer answer of #smathy.
Also just FYI, AFAIU regular expression can't be learned by scrolling a tutorial. You just need to go through the basics and try out the examples.

Some basic info.
When you read regular expressions, you read them from left to right. That's how the engine does it.
This is important in the case of alternations as the one on the left side(s) are always tried first.
But in the case of a $ (EOL or EOS) anchor, it might be easier to read from right to left.
Built-in assertions like line break anchors ^$ and word boundry \b along with normal assertions look ahead (?=)(?!) and look behind (?<=)(?<!), do not consume characters.
They are like single path in-line conditionals that pass or fail, where only if it passes will the expression to the right of it be examined. So they do actually Match something, they match a condition.
Format your regex so you can see what its doing. (Use a app to help you RegexFormat 5)
^ # BOS
[^a-zA-Z0-9]* # Optional not any alphanum chars
| # or,
[^a-zA-Z0-9]* # Optional not any alphanum chars
$ # EOS
Your regex in global context will always match twice, once at the beginning of the string, once at the end because of the line break anchors and because you don't actually require anything else to match.
So basically you should avoid trying to match (mix) all optional things with the built-in anchors ^$\b. That means your regex is better represented by ^[^a-zA-Z0-9]+|[^a-zA-Z0-9]+$ since you don't care if its NOT there (in the case of *, zero or more quantifier).
Good Luck, keep studying.

To answer your third question, the alternatives run all the way to the //s, so both sides are not the same. In the original regex the left alternative is "all non alphanumerics at the start of the string" and the right alternative is "all non alphanumerics at the end of the string".

RegEx in JS to find No 3 Identical consecutive characters

How to find a sequence of 3 characters, 'abb' is valid while 'abbb' is not valid, in JS using Regex (could be alphabets,numerics and non alpha numerics).
This question is a variation of the question that I have asked in here : How to combine these regex for javascript.
This is wrong : /(^([0-9a-zA-Z]|[^0-9a-zA-Z]))\1\1/ , so what is the right way to do it?

This depends on what you actually mean. If you only want to match three non-identical characters (that is, if abb is valid for you), you can use this negative lookahead:
(?!(.)\1\1).{3}
It first asserts, that the current position is not followed by three times the same character. Then it matches those three characters.
If you really want to match 3 different characters (only stuff like abc), it gets a bit more complicated. Use these two negative lookaheads instead:
(.)(?!\1)(.)(?!\1|\2).
First match one character. Then we assert, the this is not followed by the same character. If so, we match another character. Then we assert that these are followed neither by the first nor the second character. Then we match a third character.
Note that those negative lookaheads ((?!...)) do not consume any characters. That is why they are called lookaheads. They just check what is coming next (or in this case what is not coming next) and then the regex continues from where it left of. Here is a good tutorial.
Note also that this matches anything but line breaks, or really anything if you use the DOTALL or SINGLELINE option. Since you are using JavaScript you can just activate the option by appending s after the regexes closing delimiter. If (for some reason) you don't want to use this option, replace the .s by [\s\S] (this always matches any character).
Update:
After clarification in the comments, I realised that you do not want to find three non-identical characters, but instead you want to assert that your string does not contain three identical (and consecutive) characters.
This is a bit easier, and closer to your former question, since it only requires one negative lookahead. What we do is this: we search the string from the beginning for three consecutive identical characters. But since we want to assert that these do not exist we wrap this in a negative lookahead:
^(?!.*(.)\1\1)
The lookahead is anchored to the beginning of the string, so this is the only place where we will look. The pattern in the lookahead then tries to find three identical characters from any position in the string (because of the .*; the identical characters are matched in the same way as in your previous question). If the pattern finds these, the negative lookahead will thus fail, and so the string will be invalid. If not three identical characters can be found, the inner pattern will never match, so the negative lookahead will succeed.

To find non-three-identical characters use regex pattern
([\s\S])(?!\1\1)[\s\S]{2}

Please explain some Javascript Regular Expressions

I'm learning Javascript via an online tutorial, but nowhere on that website or any other I googled for was the jumble of symbols explained that makes up a regular expression.
Check if all numbers: /^[0-9]+$/
Check if all letters: /^[a-zA-Z]+$/
And the hardest one:
Validate Email: /^[\w-.+]+\#[a-zA-Z0-9.-]+.[a-zA-z0-9]{2,4}$/
What do all the slashes and dollar signs and brackets mean? Please explain.
(By the way, what languages are required to create a flexible website? I know a bit of Javascript and wanna learn jQuery and PHP. Anything else needed?)
Thanks.

There are already a number of good sites that explain regular expressions so I'll just dive a bit into how each of the specific examples you gave translate.
Check if all numbers: ^ anchors the start of the expression (e.g. start at the beginning of the text). Without it a match could be found anywhere. [0-9] finds the characters in that character class (e.g. the numbers 0-9). The + after the character class just means "one or more". The ending $ anchors the end of the text (e.g. the match should run to the end of the input). So if you put that together, that regular expression would allow for only 1 or more numbers in a string. Note that the anchors are important as without them it might match something like "foo123bar".
Check if all letters: Pretty much the same as above but the character classes are different. In this example the character class [a-zA-Z] represents all lowercase and uppercase characters.
The last one actually isn't any more difficult than the other two it's just longer. This answer is getting quite long so I'll just explain the new symbols. A \w in a character class will match word characters (which are defined per regex implementation but are generally 0-9a-zA-Z_ at least). The backslash before the # escapes the # so that it isn't seen as a token in the regex. A period will match any character so .+ will match one or more of any character (e.g. a, 1, Z, 1a, etc). The last part of the regex ({2,4}) defines an interval expression. This means that it can match a minimum of 2 of the thing that precedes it, and a maximum of 4.
Hope you got something out of the above.

There is an awesome explanation of regular expressions at http://www.regular-expressions.info/ including notes on language and implementation specifics.

Let me explain:
Check if all numbers: /^[0-9]+$/
So, first thing we see is the "/" at the beginning and the end. This is a deliminator, and only serves to show the beginning and end of the regular expression.
Next, we have a "^", this means the beginning of the string. [0-9] means a number from 0-9. + is a modifier, which modifies the term in front of it, in this case, it means you can have one or more of something, so you can have one or more numbers from 0-9.
Finally, we end with "$", which is the opposite of "^", and means the end of the string. So put that all together and it basically makes sure that inbetween the start and end of the string, there can be any number of digits from 0-9.
Check if all letters: /^[a-zA-Z]+$/
We notice this is very similar, but instead of checking for numbers 0-9, it checks for letters a-z (lowercase) and A-Z (uppercase).
And the hardest one:
Validate Email: /^[\w-.+]+\#[a-zA-Z0-9.-]+.[a-zA-z0-9]{2,4}$/
"\w" means that it is a word, in this case we can have any number of letters or numbers, as well as the period means that it can be pretty much any character.
The new thing here is escape characters. Many symbols cannot be used without escaping them by placing a slash in front, as is the case with "\#". This means it is looking directly for the symbol "#".
Now it looks for letters and symbols, a period (this one seems incorrect, it should be escaping the period too, though it will still work, since an unescaped period will make any symbol). Numbers inside {} mean that there is inbetween this many terms in the previous term, so of the [a-zA-Z0-9], there should be 2-4 characters (this part here is the website domain, such as .com, .ca, or .info). Note there's another error in this one here, the [a-zA-z0-9] should be [a-zA-Z0-9] (capital Z).
Oh, and check out that site listed above, it is a great set of tutorials too.

Regular Expressions is a complex beast and, as already pointed out, there are quite a few guides off of google you can go read.
To answer the OP questions:
Check if all numbers: /^[0-9]+$/
regexps here are all delimated with //, much like strings are quoted with '' or "".
^ means start of string or line (depending on what options you have about multiline matching)
[...] are called character classes. Anything in [] is a list of single matching characters at that position in this case 0-9. The minus sign has a special meaning of "sequence of characters between". So [0-9] means "one of 0123456789".
+ means "1 or more" of the preceeding match (in this case [0-9]) so one or more numbers
$ means end of string/line match.
So in summary find any string that contains only numbers, i.e '0123a' will not match as [0-9]+ fails to match a before $).
Check if all letters: /^[a-zA-Z]+$/
Hopefully [A-Za-z] makes sense now (A-Z = ABCDEF...XYZ and a-z abcdef...xyz)
Validate Email: /^[\w-.+]+\#[a-zA-Z0-9.-]+.[a-zA-z0-9]{2,4}$/
Not all regexp parses know the \w sequence. Javascript, java and perl I know do support it.
I have already have covered '/^ at the beginning, for this [] match we are looking for
\w - . and +. I think that regexp is incorrect. Either the minus sign should be escaped with \ or it should be at the end of the [] (i.e [\w+.-]). But that is an aside they are basically attempting to allow anything of abcdefghijklmnopqrstuvwxyz01234567890-.+
so fred.smith-foo+wee#mymail.com will match but fred.smith%foo+wee#mymail.com wont (the % is not matched by [\w.+-]).
\# is the litteral atsil sign (it is escaped as perl expands # an array variable reference)
[a-zA-Z0-9.-]+ is the same as [\w.-]+. Very much like the user part of the match, but does not match +. So this matches foo.com. and google.co. but not my+foo.com or my***domain.co.
. means match any one character. This again is incorrect as fred#foo%com will match as . matches %*^%$£! etc. This should of been written as \.
The last character class [a-zA-z0-9]{2,4} looks for between 2 3 or 4 of the a-zA-Z0-9 specified in the character class (much like + looks for "1 more more" {2,4} means at least 2 with a maximum of 4 of the preceeding match. So 'foo' matches, '11' matches, '11111' does not match and 'information' does not.
The "tweaked" regexp should be:
/^[\w.+-]+\#[a-zA-Z0-9.-]+\.[a-zA-z0-9]{2,4}$/

I'm not doing a tutorial on RegEx's, that's been done really well already, but here are what your expressions mean.
/^<something>$/ String begins, has something in the middle, and then immediately ends.
/^foo$/.test('foo'); // true
/^foo$/.test('fool'); // false
/^foo$/.test('afoo'); // false
+ One or more of something:
/a+/.test('cot');//false
/a+/.test('cat');//true
/a+/.test('caaaaaaaaaaaat');//true
[<something>] Include any characters found between the brackets. (includes ranges like 0-9, a-z, and A-Z, as well as special codes like \w for 0-9a-zA-Z_-
/^[0-9]+/.test('f00')//false
/^[0-9]+/.test('000')//true
{x,y} between X and Y occurrences
/^[0-9]{1,2}$/.test('12');// true
/^[0-9]{1,2}$/.test('1');// true
/^[0-9]{1,2}$/.test('d');// false
/^[0-9]{1,2}$/.test('124');// false
So, that should cover everything, but for good measure:
/^[\w-.+]+\#[a-zA-Z0-9.-]+.[a-zA-z0-9]{2,4}$/
Begins with at least character from \w, -, +, or .. Followed by an #, followed by at least one in the set a-zA-Z0-9.- followed by one character of anything (. means anything, they meant \.), followed by 2-4 characters of a-zA-z0-9
As a side note, this regular expression to check emails is not only dated, but it is very, very, very incorrect.