Lets say I want to match urls, which are not inside a specific set of attributes in html tags.
<span cstm1="url1" cstm2="url2" data-x="url3">url4</span>
I want to match url3 and url4 only, so I tried something like:
/(?!(?:cstm1|cstm2)=["']?)(url_regex)/g
problem is that the negative look ahead assertion need something before it and I cannot ensure that the number cannot be inside quotes because it'll still be valid, so I don't have anything reasonable to put behind this negative look ahead assertion.
If I was able to use negative look behind assertion it'll be really easy, but I'm using javascript which doesn't support it, so I'm kinda stuck and looking for help on how to achieve this.
I look for regex only solution.
EDIT:
The url regex I used to find urls:
((?:(?:https?):\/\/)(?:\S+(?::\S*)?#)?(?:(?!10(?:\.\d{1,3}){3})(?!127(?:\.\d{1,3}){3})(?!169\.254(?:\.\d{1,3}){2})(?!192\.168(?:\.\d{1,3}){2})(?!172\.(?:1[6-9]|2\d|3[0-1])(?:\.\d{1,3}){2})(?:[1-9]\d?|1\d\d|2[01]\d|22[0-3])(?:\.(?:1?\d{1,2}|2[0-4]\d|25[0-5])){2}(?:\.(?:[1-9]\d?|1\d\d|2[0-4]\d|25[0-4]))|\[(?:(?:[0-9a-fA-F]{1,4}:){7,7}[0-9a-fA-F]{1,4}|(?:[0-9a-fA-F]{1,4}:){1,7}:|(?:[0-9a-fA-F]{1,4}:){1,6}:[0-9a-fA-F]{1,4}|(?:[0-9a-fA-F]{1,4}:){1,5}(?::[0-9a-fA-F]{1,4}){1,2}|(?:[0-9a-fA-F]{1,4}:){1,4}(?::[0-9a-fA-F]{1,4}){1,3}|(?:[0-9a-fA-F]{1,4}:){1,3}(?::[0-9a-fA-F]{1,4}){1,4}|(?:[0-9a-fA-F]{1,4}:){1,2}(?::[0-9a-fA-F]{1,4}){1,5}|[0-9a-fA-F]{1,4}:(?:(?::[0-9a-fA-F]{1,4}){1,6})|:(?:(?::[0-9a-fA-F]{1,4}){1,7}|:)|fe80:(?::[0-9a-fA-F]{0,4}){0,4}%[0-9a-zA-Z]{1,}|::(?:ffff(?::0{1,4}){0,1}:){0,1}(?:(?:25[0-5]|(?:2[0-4]|1{0,1}[0-9]){0,1}[0-9]).){3,3}(?:25[0-5]|(?:2[0-4]|1{0,1}[0-9]){0,1}[0-9])|(?:[0-9a-fA-F]{1,4}:){1,4}:(?:(?:25[0-5]|(?:2[0-4]|1{0,1}[0-9]){0,1}[0-9]).){3,3}(?:25[0-5]|(?:2[0-4]|1{0,1}[0-9]){0,1}[0-9]))\]|localhost|(?:xn--[a-z0-9\-]{1,59}|(?:(?:[a-z\u00a1-\uffff0-9]+-?){0,62}[a-z\u00a1-\uffff0-9]{1,63}))(?:\.(?:xn--[a-z0-9\-]{1,59}|(?:[a-z\u00a1-\uffff0-9]+-?){0,62}[a-z\u00a1-\uffff0-9]{1,63}))*(?:\.(?:xn--[a-z0-9\-]{1,59}|(?:[a-z\u00a1-\uffff]{2,63}))))(?::\d{2,5})?(?:\/[^"'()<>\s]*)?)
In the absence of lookbehind you can use capture group to extract your results.
/(?:cstm1|cstm2)=(['"]?)\d+\1|(\b\d+\b)/ig
Use captured group #2 for your matches.
RegEx Demo
IE (<9?) doesn't tolerate trailing commas at the end of object or list.
I know this too late, after developing for a few months in Chrome.
Now I have to search for every place I put in a trail comma, this is really painful.
Is there any way(preferably automatic) to do this? Like a editor plugin, or some script that search and replace these commas with blank?
JSLint is an option, but it throws a lot of other warnings, and I have to paste in the scripts (which sometimes contain server-side template tags...).
Some examples would have been good and which editor you use.
Notepad++ and UltraEdit support both Perl regular expression replaces with back referencing.
So you could try a Perl regular expression replace searching with the expression ,(\s*?[)\]]) and using \1 as replace string.
This expression finds a comma before a closing round or square bracket with 0 or more spaces/tabs/line terminators between and keeps on replace everything except the comma.
You should run this replace manually on your JavaScript code with checking what is found before making the replace. And perhaps you need to run this replace several times in case of multiple commas at end of a list.
IDEA will not allow this error and i have not been able to find an option to turn off these kinds of errors. does anyone know how to fix the error or turn off the warning. The javascript works fine only IDEA sees this as a problem
You are creating a range by using the hyphen(-) in mid of your character class. You should move it to either end.
Also, note that you don't need to escape the regex meta-characters inside the character class. They loose their meanings in there.
So, just use:
[-\w._+%]
I trying to make a regex for finding: background-image:url('URL'); Where the URL is a external link for an image.
Been trying for something like this:
/\s*?[ \t\n]background-image:url('https?:\/\/(?:[a-z\-]+\.)+[a-z]{2,6}(?:\/[^\/#?]+)+\.(?:jpe?g|gif|png)$');/i
But couldn't get it to work.
I am using this with javascript/jquery
Does this get what you want?:
/\s*?[ \t\n]background-image:url\('.+?'\);/i
I think you can simplify it to this if you know it will only change with the URL in the middle. I probably went overboard with the \ escapes but better to be safe than sorry.
/background\-image\:url\(\'.*?\'\)\;/
Epascarello hit the nail on the head. Is this source you control? Or at least a predictable website? What are multiple different examples of input and your expected results?
Will this always be inline in double quotes, and therefore your URL will always be in single quotes? Some old websites use double-quotes in their CSS Files or header CSS.
Do you want to capture the whole thing? Or are you just trying to extract the resulting URL?
SirCapsAlot brings up a good question, are you just looking for background image URL's in general? Because they can use the Background property also, or even be set in JavaScript with .backgroundImage="url(image.jpg)".
And you definitely only want the ones that include http(s)?
With the limited requirements you gave, this is the best Regex:
background-image\s*:\s*url\('(https?://[^']+)
Comment here if you have answers to my questions which may alter your requirements, and thusly my answer.
Breakdown:
background-image:\s*url //Find the literal text to begin
\(' //Find the literal opening parens and quote
( //Begin Capture Group 1
https?:// //Require the match of https:// (the s is optional because of the ?)
[^']+ //Require that everything until the next quote is matched
) //Capture the result into Group 1
A Co-Worker pointed out that I might have been downvoted for not capturing the closing tick. Note: Capturing the closing tick would be a wasted step, and is not necessary for this regex to work.
He also pointed out somebody might have downvoted me for requiring http or https in the url portion. But the user's question was specifically for external URLs, not internal ones. So this is a valid requirement and gets him closer to what he asked.
Sooo... not sure why this got a downvote.
I seem to have backed myself up into a corner with this. I'm sure that the answer is going to make me want to smack a brick against my head, but I'm not all that good with regex just yet. So, here goes.
I need to modify this regex so that it fails if it finds any occurances of pound signs. (#)
My current regex is this;
/^[A-Za-z\.\-\_\s]{1,80}$/i
I tried a number of variations such as;
/[^#]^[A-Za-z\.\-\_\s]{1,80}$/i
/^[[^#]A-Za-z\.\-\_\s]{1,80}$/i
/^[A-Za-z\.\-\_\s^#]{1,80}$/i
None of which work. Can anyone offer any advise, please?
Your original regex should work, because # isn't in the list of characters you specified for the class. You don't need to add anything, it already fails if there's a # in there.
Just use two regexes:
/^[A-Za-z\.\-\_\s]{1,80}$/i
Then filter your input so that you keep only what does NOT match this regex:
/#/
It's far easier to match on patterns that you want to filter out (and then ignoring the matching strings instead of ignoring the complement) than it is to try to construct an "inverse" regex. And there's no reason why you should try to fit everything into one regex.