I have a small problem with JavaScript regexp.
I want to match a part of the html class, something like:
req_password_sameAs-myid_min-6
A want to match sameAs-myid only, but with idea that there is a possibility to not have other characters after this string for example:
req_password_sameAs-myid
is also an option.
I use this expression
detectCase[i].match(/sameAs-.*?(_|)/g)
but don't know how to tell regexp _ or no characters as you can see.
Thank you in advance
Regex quantifiers. _? is the same as _{0,1}, means 'an underscore or nothing'.
You should be more specific than .*?. That's your problem, not the syntactically correct (but ugly) way of making the underscore optional.
Try
/sameAs-[a-zA-Z]*/g
Related
I'm creating a javascript regex to match queries in a search engine string. I am having a problem with alternation. I have the following regex:
.*baidu.com.*[/?].*wd{1}=
I want to be able to match strings that have the string 'word' or 'qw' in addition to 'wd', but everything I try is unsuccessful. I thought I would be able to do something like the following:
.*baidu.com.*[/?].*[wd|word|qw]{1}=
but it does not seem to work.
replace [wd|word|qw] with (wd|word|qw) or (?:wd|word|qw).
[] denotes character sets, () denotes logical groupings.
Your expression:
.*baidu.com.*[/?].*[wd|word|qw]{1}=
does need a few changes, including [wd|word|qw] to (wd|word|qw) and getting rid of the redundant {1}, like so:
.*baidu.com.*[/?].*(wd|word|qw)=
But you also need to understand that the first part of your expression (.*baidu.com.*[/?].*) will match baidu.com hello what spelling/handle????????? or hbaidu-com/ or even something like lkas----jhdf lkja$##!3hdsfbaidugcomlaksjhdf.[($?lakshf, because the dot (.) matches any character except newlines... to match a literal dot, you have to escape it with a backslash (like \.)
There are several approaches you could take to match things in a URL, but we could help you more if you tell us what you are trying to do or accomplish - perhaps regex is not the best solution or (EDIT) only part of the best solution?
I'm trying to write a regex to test for certain special characters, but I think I am overcomplicating things. The characters I need to check for are: &<>'"
My current regex looks like such:
/&<>'"/
Another I was trying is:
/\&\<\>\'\"/
Any tips for a beginner (in regards to regex)? Thanks!
You are looking for a character class:
/[&<>'"]/
In doing so, any of the characters in the square brackets will be matched.
The expression you were originally using, /&<>'"/, wasn't working as expected because it matches the characters in that sequential order. In other words, it would match a full string such as &<>'" but not &<.
I'm assuming that you want to be able to match all of the characters you listed, at one time.
If so, you should be able to combine a character set with the g (global-matching) flag, for your regex.
Here's what it could look like:
/[<>&'"]/g
Try /(\&|\<|>|\'|\")/
it depends on what regex system you use
Can someone please explain the syntax of searching through strings? For example, I have this piece of code:
var ok = phone.value.search(/^\d{3}-\d{4}$/);
phone is a variable that is supposed to contain a phone number, and I know from context that this is supposed to make sure the inputted number has the format ###-####, but I don't know what the code within the parenthesis means or how it is evaluated. If someone has a link explaining how to use code like that I would especially appreciate it.
That's a regular expression ( regex ),
Regex One has a good guide on how to use them
Your regex says "beginning with 3 digits, then a "-" then 4 digits"
It's a regular expression, a whole world in itself.
http://www.regular-expressions.info/tutorial.html
It is regex object. The ^ matches the beggining of the string, the \d{3} matches 3 digits, the - matches a dash, the \d{4} matches for digits, and finally the $ matches the end of the string.
What you have there is called a "regular expression" and as you say, they are used to ensure input matches a certain pattern. I recommend you go somewhere like http://www.regular-expressions.info/ for further info rather than re-post data here.
I am a Regex newbie and trying to implement Regex to replace a matching pattern in a string only when it has a ( - open parentheses using Javascript. for example if I have a string
IN(INTERM_LEVEL_IN + (int)X_ID)
I would only like to highlight the first IN( in the string. Not the INTERM_LEVEL_IN (2 ins here) and the int.
What is the Regex to accomplish this?
To match the opening bracket you just need to escape it: IN\(.
For instance, running this in Firebug console:
enter code here"IN(INTERM_LEVEL_IN + (int)X_ID)".replace(/(IN()/, 'test');`
Will result in:
>>> "IN(INTERM_LEVEL_IN + (int)X_ID)".replace(/(IN\()/, 'test');
"testINTERM_LEVEL_IN + (int)X_ID)"
Parenthesis in regular expressions have a special meaning (sub-capture groups), so when you want them to be interpreted literally you have to escape them by with a \ before them. The regular expression IN\( would match the string IN(.
The following should only match IN( at the beginning of a line:
/^IN\(/
The following would match IN( that is not preceded by any alphanumeric character or underscore:
/[a-zA-Z0-9_]IN\(/
And finally, the following would match any instance of IN( no matter what precedes it:
/IN\(/
So, take your pick. If you're interested in learning more about regex, here's a good tutorial: http://www.regular-expressions.info/tutorial.html
You can use just regular old Javascript for regex, a simple IN\( would work for the example you gave (see here), but I suspect your situation is more complicated than that. In which case, you need to define exactly what you are trying to match and what you don't want to match.
I have been trying to use a regexp that matches any text that is between a caret, less than and a greater than, caret.
So it would look like: ^< THE TEXT I WANT SELECTED >^
I have tried something like this, but it isn't working: ^<(.*?)>^
I'm assuming this is possible, right? I think the reason I have been having such a tough time is because the caret serves as a quantifier. Thanks for any help I get!
Update
Just so everyone knows, they following from am not i am worked
/\^<(.*?)>\^/
But, it turned out that I was getting html entities since I was getting my string by using the .innerHTML property. In other words,
> ... >
< ... <
To solve this, my regexp actually looks like this:
\^<(.*?)((.|\n)*)>\^
This includes the fact that the string in between should be any character or new line. Thanks!
You need to escape the ^ symbol since it has special meaning in a JavaScript regex.
/\^<(.*?)>\^/
In a JavaScript regex, the ^ means beginning of the string, unless the m modifier was used, in which case it means beginning of the line.
This should work:
\^<(.*?)>\^
In a regex, if you want to use a character that has a special meaning (caret, brackets, pipe, ...), you have to escape it using a backslash. For example, (\w\b)*\w\. will select a sequence of words terminated by a dot.
Careful!
If you have to pass the regex pattern as a string, i.e. there's no regex literal like in javascript or perl, you may have to use a double backslash, which the programming language will escape to a single one, which will then be processed by the regex engine.
Same regex in multiple languages:
Python:
import re
myRegex=re.compile(r"\^<(.*?)>\^") # The r before the string prevents backslash escaping
PHP:
$result=preg_match("/\\^<(.*?)>\\^/",$subject); // Notice the double backslashes here?
JavaScript:
var myRegex=/\^<(.*?)>\^/,
subject="^<blah example>^";
subject.match(myRegex);
If you tell us what programming language you're writing in, we'll be able to give you some finished code to work with.
Edit: Whoops, didn't even notice this was tagged as javascript. Then, you don't have to worry about double backslash at all.
Edit 2: \b represent a word boundary. Though I agree yours is what I would have used myself.