Develop Reference

How to use if condition in Javascript RegEx?

I am trying to add some rules to Imagus Firefox Extension. I want to capture image parameter from Google Image Search and if it contains the string th_ remove it and redirect. Otherwise just redirect.
This is my RegEx:
/^(?:(?:images|encrypted)\.)?google\.[^/]+/(?:imgres\?(?:[^&]+&)*?imgurl=)(.*)(?:th_)(.*)&imgrefurl=.*/gm
It works fine for URL's which contain string th_ but for other links it breaks.
Here's the link to my work https://regexr.com/3omf5 Have a look and help. PS: Please note there are two links in the example.

I found the answer after a fight. And the regex works fine in the Extension.
Ans:
^(?:(?:images|encrypted)\.)?google\.[^/]+/(?:imgres\?(?:[^&]+&)*?imgurl=)(.*)(%2Fimages(?:[\d]{1,9})?%2F)(th_)?(.*)&imgrefurl=.*
Here is th link with answer:
https://regexr.com/3omfh

Add a * after (?:th_), like:
^(?:(?:images|encrypted)\.)?google\.[^/]+/(?:imgres\?(?:[^&]+&)*?imgurl=)(.*)(?:th_)*(.*)&imgrefurl=.*

^(?:(?:(?:images|encrypted)\.)?google\.[^/]+/(?:imgres\?(?:[^&]+&)*?imgurl=)(.*)(?:th_)(.*)&imgrefurl=.*)|(.+)
Matches your urls with th_ and replaces it or takes the whole url with the additional |(.+) (+ ^(?: ... ) around your regex). You need to replace it with $1$2$3 then

Detect protocol optional url in text with Javascript

I found a lot of answers to detect url in text. I tried them but failed to detect protocol optional urls. Most of existing solutions could find urls in "Hello, open http://somesite.com/etc to see my photo" and replace the http part to tags. But they could not work for cases like "Hey, open somesite.com or somesite.com/etc to take a look."
How can I detect both cases (better with one regex), and the default protocol is "http://" for none-protocol urls.
I note that SO also failed to detect the latter case...
Edit:
Maybe it is error-prone to change somesite.com into urls (in English), so this requirement is not ideal?
I used regex /(https?://[^\s]+)/g. This one is simple and support cases like http://abcd.com/etc/?v=3&type=xyz. But I don't know how to change it to support protocol absent case.

You can use this:
^(https?:\/\/)?\w+\.\w+([\/\w\?\-\+\!\&\$\=\.\:]+)*$
Matches:
www.domain.com
http://www.domain.com
http://www.somesite.com/etc
http://www.somesite.com/etc/etc/etc
somesite.com
somesite.com/etc
http://google.com/q=regex+for+this&utm-source=stackoverflow
DEMO

This isn't bullet proof, but it works with the example you've provided:
var text = "Hey, open some-site.com or somesite.com/etc?test=1 to take a look."
var myregexp = /([\-A-Z0-9+&##\/%=~_|]+\.[a-z]{2,7})(\/[\-A-Z0-9+&##\/%=~_|?]+)?/ig;
var result = text.replace(myregexp, '$1$2');
alert(result);
//Hey, open some-site.com or somesite.com/etc?test=1 to take a look.
LIVE DEMO

Only match regex if it doesnt start with a pattern in javascript

I have a bit of a strange one here, I basically have a large chunk of text which may or may not contain links to images.
So lets say it does I have a pattern which will extract the image url fine, however once a match is found it is replaced with a element with the link as the src. Now the problem is there may be multiple matches within the text and this is where it gets tricky. As the url pattern will now match the src tags url, which will basically just enter an infinite loop.
So is there a way to ONLY match in regex if it doesnt start with a pattern like ="|=' ? as then it would match the url in something like:
some image http://cdn.sstatic.net/stackoverflow/img/sprites.png?v=6
but not
some image <img src="http://cdn.sstatic.net/stackoverflow/img/sprites.png?v=6">
I am not sure if it is possible, but if it is could someone point me in the right direction? A replace by itself will not suffice in this scenario as the url matched needs to be used elsewhere too so it needs to be used like a capture.
The main scenarios I need to account for are:
Many links in one block of varied text
A single link without any other text
A single link with other varied text
== edit ==
Here is the current regex I am using to match urls:
(\b(https?|ftp|file):\/\/[-A-Z0-9+&##\/%?=~_|!:,.;]*(?:png|jpeg|jpg|gif|bmp))
== edit 2 ==
Just so everyone understands why I cannot use the /g command here is an answer which explains the issue, if I could use this /g like I originally tried then it would make things a lot simpler.
Javascript regex multiple captures again

What you are looking for is a negative look behind, but Javascript doesn't support any kind of look behinds, so you will either have to use a callback function to check what was matched and make sure it is not preceded by a ' or ", or you can use the following regex:
(?:^|[^"'])(\b(https?|ftp|file):\/\/[-a-zA-Z0-9+&##\/%?=~_|!:,.;]*(?:png|jpeg|jpg|gif|bmp))
which has a single problem, that is in the case of a successful match it will catch one more character, the one right before the (\b(https?|ftp|file) pattern in the input, but I think you can deal with this easily.
Regex101 Demo

Using the /ig command at the end should work... the g is for global replace and the i is for case-insensitivity, which is necessary as you've only got A-Z instead of a-zA-Z.
Using the following vanilla JS appears to work for me (see jsfiddle)...
var test="some image http://cdn.sstatic.net/stackoverflow/img/sprites.png?v=6 some image http://cdn.sstatic.net/stackoverflow/img/sprites.png?v=6 some image http://cdn.sstatic.net/stackoverflow/img/sprites.png?v=6";
var re = new RegExp(/(\b(https?|ftp|file):\/\/[-A-Z0-9+&##\/%?=~_|!:,.;]*(?:png|jpeg|jpg|gif|bmp))/ig);
document.getElementById("output").innerHTML = test.replace(re,"<img src=\"$1\"/>");
Although, what it does highlight is that the query string part of the URL (the ?v=6 is not being picked up with your RegEx).
For jQuery, it would be (see jsfiddle)...
$(document).ready(function(){
var test="some image http://cdn.sstatic.net/stackoverflow/img/sprites.png?v=6 some image http://cdn.sstatic.net/stackoverflow/img/sprites.png?v=6 some image http://cdn.sstatic.net/stackoverflow/img/sprites.png?v=6";
var re = new RegExp(/(\b(https?|ftp|file):\/\/[-A-Z0-9+&##\/%?=~_|!:,.;]*(?:png|jpeg|jpg|gif|bmp))/ig);
$("#output").html(test.replace(re,"<img src=\"$1\"/>"));
});
Update
Just in case my example of using the same image URL in the example doesn't convince you - it also works with different URLs... see this jsfiddle update
var test="http://cdn.sstatic.net/stackoverflow/img/sprites.png?v=6 http://cdn.sstatic.net/serverfault/img/sprites.png?v=7";
var re = new RegExp(/(\b(https?|ftp|file):\/\/[-A-Z0-9+&##\/%?=~_|!:,.;]*(?:png|jpeg|jpg|gif|bmp))/ig);
document.getElementById("output").innerHTML = test.replace(re,"<img src=\"$1\"/>");

Couldn't you just see if there is a whitespace in front of the url, instead of that word-boundary? seems to work, although you will have to remove the matched whitespace later.
(\s(https?|ftp|file):\/\/[-A-Z0-9+&##\/%?=~_|!:,.;]*(?:png|jpeg|jpg|gif|bmp))
http://rubular.com/r/9wSc0HNWas
Edit: Damn, too slow :) I'll still leave this here as my regex is shorter ;)

as was said by freefaller, you might use /g flag to just find all matches in one go, if exec is not a must.
otherwise: you can add (="|=')? to the beginning of your regex, and check if $1 is undefined. if it is undefined, then it was not started with a ="|=' pattern

Regular expression to include all specific pattern and exclude only one case

I am working something to exclude some URL.
I want to expect all URLs with the pattern /google.com/, except for /login.google.com/
So:
account.google.com should pass
google.com should pass
google.com/abc should pass
http://google.com should pass
login.google.com should not pass
The code I am trying is
/^(?!login\.)google\.com/
/^(login)google\.com/
but neither is working. Am I missing something?

Assuming you're trying to match any google.com address except ones that begin with login., you need to just add a .* prior to the google, i.e.
/^(https?:\/\/)?(?!login\.)([\w-]+\.)?google\.com/
Update: Modified based on helpful comments. Not sure what the valid domain name character class is - took a guess at that as being [\w-]. See http://rubular.com/ if you want to play with it.

This regex should work for you:
^(?:https?://)?(?!login\.)(?:.+?\.)?google\.com(?:/.*|)$
Live Demo: http://www.rubular.com/r/z69WSKV9cM
Javascript syntax:
/^(?:https?:\/\/)?(?!login\.)(?:.+?\.)?google\.com(?:\/.*|)$/

Try this pattern to match the data listed in the question:
/^(account\.)?google\.com/

Capture every URL in text [duplicate]

I have to find the first url in the text with a regular expression:
for example:
I love this website:http://www.youtube.com/music it's fantastic
or
[ es. http://www.youtube.com/music] text

I looked into this issue last year and developed a solution that you may want to look at - See: URL Linkification (HTTP/FTP) This link is a test page for the Javascript solution with many examples of difficult-to-linkify URLs.
My regex solution, written for both PHP and Javascript - is not simple (but neither is the problem as it turns out.) For more information I would recommend also reading:
The Problem With URLs by Jeff Atwood, and
An Improved Liberal, Accurate Regex Pattern for Matching URLs by John Gruber
The comments following Jeff's blog post are a must read if you want to do this right...
Note that this question gets asked a lot. Maybe do a search next time :)

You can't do this perfectly with a regular expression. You may be interested in this blog post. There is a bit more information on Regex Guru, but even those look very fragile. You will need to have additional checks outside of your regular expression to catch the edge cases.

Identifying URLs is tricky because they are often surrounded by punctuation marks and because users frequently do not use the full form of the URL. Many JavaScript functions exist for replacing URLs with hyperlinks, but I was unable to find one that works as well as the urlize filter in the Python-based web framework Django. I therefore ported Django's urlize function to JavaScript: https://github.com/ljosa/urlize.js
It actually would not pick up the URL in your example because there is a colon right before the URL. But if we modify the example a little:
urlize("I love this website: http://www.youtube.com/music it's fantastic", true, true)
=> 'I love this website: http://www.youtube.com/music it's fantastic"'
Note the second argument which, if true, inserts rel="nofollow" and the third argument which, if true, quotes characters that have special meaning in HTML.

This might work->
\b(([\w-]+://?|www[.])[^\s()<>]+(?:\([\w\d]+\)|([^[:punct:]\s]|/)))
Found it somewhere
Will find links ->
http://foo.com/blah_blah/
(Something like http://foo.com/blah_blah)
http://foo.com/blah_blah_(wikipedia)
Hope this works....

i am using this regex : :) ( its translated ABNF )
[a-zA-Z]([a-zA-Z]|[0-9]|\+|\-|\.)*:\/\/((([a-zA-Z]|[0-9]|-|\.|_|~)|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'\(\)\*\+,;=]|:)*#)?(\[((([0-9A-Fa-f]{1,4}:){6}([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9]))|::([0-9A-Fa-f]{1,4}:){5}([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9]))|([0-9A-Fa-f]{1,4})?::([0-9A-Fa-f]{1,4}:){4}([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9]))|(([0-9A-Fa-f]{1,4}:){0,1}[0-9A-Fa-f]{1,4})?::([0-9A-Fa-f]{1,4}:){3}([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9]))|(([0-9A-Fa-f]{1,4}:){0,2}[0-9A-Fa-f]{1,4})?::([0-9A-Fa-f]{1,4}:){2}([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9]))|(([0-9A-Fa-f]{1,4}:){0,3}[0-9A-Fa-f]{1,4})?::[0-9A-Fa-f]{1,4}:([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9]))|(([0-9A-Fa-f]{1,4}:){0,4}[0-9A-Fa-f]{1,4})?::([0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9]))|(([0-9A-Fa-f]{1,4}:){0,5}[0-9A-Fa-f]{1,4})?::[0-9A-Fa-f]{1,4}|(([0-9A-Fa-f]{1,4}:){0,6}[0-9A-Fa-f]{1,4})?::)|v[0-9A-Fa-f]\.(([a-zA-Z]|[0-9]|-|\.|_|~)|[!$&'\(\)\*\+,;=]|:))\]|(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9])|(([a-zA-Z]|[0-9]|-|\.|_|~)|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'\(\)\*\+,;=])*)(:[0-9]*)?(((\/(([a-zA-Z]|[0-9]|-|\.|_|~)|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'\(\)\*\+,;=]|:|#)*)*|\/((([a-zA-Z]|[0-9]|-|\.|_|~)|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'\(\)\*\+,;=]|:|#){1}(\/(([a-zA-Z]|[0-9]|-|\.|_|~)|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'\(\)\*\+,;=]|:|#)*)*)?|(([a-zA-Z]|[0-9]|-|\.|_|~)|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'\(\)\*\+,;=]|:|#){1}(\/(([a-zA-Z]|[0-9]|-|\.|_|~)|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'\(\)\*\+,;=]|:|#)*)*|(([a-zA-Z]|[0-9]|-|\.|_|~)|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'\(\)\*\+,;=]|#){1}(\/(([a-zA-Z]|[0-9]|-|\.|_|~)|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'\(\)\*\+,;=]|:|#)*)*))?\/?(\?((([a-zA-Z]|[0-9]|-|\.|_|~)|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'\(\)\*\+,;=]|:|#)|\/|\?)*)?(\#((([a-zA-Z]|[0-9]|-|\.|_|~)|%[0-9A-Fa-f][0-9A-Fa-f]|[!$&'\(\)\*\+,;=]|:|#)|\/|\?)*)?

You can use the following regex expression for extracting any type of url coming in message.
String regex = "(http(s)?:\/\/.)?(www\.)?[-a-zA-Z0-9#:%._\+~#=]{2,256}\.[a-z]{2,6}\b([-a-zA-Z0-9#:%_\+.~#?&/=]*)";

Typescript/Angular
This works for me:
const regExpressionUrl = new RegExp(/(https?:\/\/[^\s]+)/g); //detect URL
Ref: https://www.regextester.com/96249%7CRegular