This question already has an answer here:
Checking symbols in string in Javascript
(1 answer)
Closed 8 years ago.
Hi I have to find a pattern in Javascript where each letter present must be preceded and followed by + sign.
Is there a way to achieve that using regex?
Suppose if my string is ++3+4++3+ , it is true
whereas if my string is 3+4++3+, it is false
You can use this regex:
/^(\++\d+(?=\+))+\++$/
Code:
var re = /^(\++\d+(?=\+))+\++$/;
var s1 = '++3+4++3+'
var s2 = '3+4++3+'
re.test(s1);
true
re.test(s2);
false
RegEx Demo
((+)+[0-9])+(++)
This says (match one or more of +, match one [0-9]) one or more times, match at least one + at the end of the string
++3+4++3+ == true
3+4++3+ == false
This site saves many hours of regex suffering: http://www.regexr.com/
JS:
var str = "++3+4++3+";
var patt = /((\+)+[0-9])+(\++)/;
var result = patt.test(str);
Related
This question already has answers here:
Regex matching 5-digit substrings not enclosed with digits
(2 answers)
Closed 2 years ago.
I am creating a function that replaces the string with a
~(number)~.
Now let's say I have a string that says
This is the replacement of ~26~ and ~524~. We still have 2 cadets left. Have2go for the next mission.2
I want to replace all the 2 in a string with ~86~ but when I am doing so the 2 in ~26~ and ~524~ also getting replaced to ~~86~6~ and ```~5~86~4~.
function replaceGameCoordinate() {
var string = `This is the replacement of ~26~ and ~524~. We still have 2 cadets left. Have2go for the next mission.2`
var replaceArr = ['2'];
let patt = new RegExp(`${replaceArr[0]}`, 'gm')
var newString = string.replace(patt, "~86~");
console.log(newString);
}
replaceGameCoordinate();
The expected output should be :
This is the replacement of ~26~ and ~524~. We still have ~86~ cadets left. Have~86~go for the next mission.~86~
So you need a different regex rule. You don't want to replace 2. You want to replace 2 when it's not next to another number or ~.
In order to do this, you can use lookaheads and lookbehinds (although lookbehinds are not yet supported by regexes in JS, I believe, but at least with lookaheads) :
const input = "This is the replacement of ~26~ and ~524~. We still have 2 cadets left. Have2go for the next mission.2";
const regex = /2(?![\d~])/gm // Means : "2 when it's not followed by a digit \d or a ~"
console.log( input.replace(regex, "~86~" ) )
This question already has answers here:
How to tell if a string contains a certain character in JavaScript?
(21 answers)
Closed 4 years ago.
I'm a beginner in node.js so please do excuse me if my question is foolish. As we know we can use
var regex = /[ !##$%^&*()_+\-=\[\]{};':"\\|,.<>\/?]/g;
regex.test(str);
to check whether a string contains special charecters or not .But what I'm asking is how to check for only a particular charecter means how can I check only presence of #.
I tried to do
var regex = /[#]/g; regex.test(str).
Although it's not working but are there any other method of doing this?
You don't need a regex to find a single character in a string. You can use indexOf, like this:
var hasHashtag = str.indexOf('#') >= 0;
This returns true if the character is in the string.
Use includes to check the existence of # in your string. You don't actually require regex to do that.
var str = 'someSt#ring';
var res = str.includes('#');
console.log(res);
str = 'someSt#ri#ng';
res = str.includes('#');
console.log(res);
str = 'someString';
res = str.includes('#');
console.log(res);
Use indexOf
str.indexOf('#') >= 0;
This question already has answers here:
How can I remove a character from a string using JavaScript?
(22 answers)
Closed 5 years ago.
I'm looking on how to remove a char from a string for example let's say i have "#22UP0G0YU" i want it to remove the # from it how would i do? I also have a small little other question too about how to make string upper case as well thanks in advance.
To remove a specific char I normally use replace, also good for a set of chars:
var str = '#22UP0G0YU';
var newString = str.replace('#', ''); // result: '22UP0G0YU'
To Uppercase, just use .toUpperCase();
var str = '#22UP0G0yu';
var newString = str.replace('#', '').toUpperCase(); // result: '22UP0G0YU'
This question already has answers here:
My regex is matching too much. How do I make it stop? [duplicate]
(5 answers)
Closed 6 years ago.
I've got a couple strings and I need to pull characters out that appear between double quotes. The problem is, I want to grab them in groups.
var str = 'FF\"J"A4"L"';
var results = str.match(/\"(.*)\"/);
This returns everything between the first and last double quote. In this case it returns J"A4"L but what I need it to return is J and L.
The content between quotes is pretty much any unicode character like letters and numbers including as }, =, and #.
Any ideas on how to complete this with regex?
It sounds like the content between quotes is any character except for a quote, in which case you can get away with
/"([^"]*)"/
what you're looking for is this with the /g "global flag":
/("[^"]*")/g
In your example, it's like this:
var str = 'FF\"J"A4"L"';
var results = str.match(/("[^"]*")/g);
When doing this, results would be [""J"", ""L""], which contains the entire match (which is why the extra quotes are there).
If you wanted just the matched groups (which returns just the groups, not the whole match area), you would use exec:
var str = 'FF\"J"A4"L"';
var results = []
var r = /("[^"]*")/g
match = r.exec(str);
while (match != null) {
results.push(match[1])
match = r.exec(str);
}
Now, results is ["J", "L"]
This question already has answers here:
Regular expression greater than and less than
(3 answers)
Closed 8 years ago.
I need a regular expression that replaces the greater than and less than symbol on a string
i already tried
var regEx = "s/</</g;s/>/>/g"
var testString = "<test>"
alert(testString.replace(regEx,"*"))
My first time to use it please go easy on me :)
Thanks
You can use regEx | like
var regEx = /<|>/g;
var testString = "<test>"
alert(testString.replace(regEx,"*"))
Fiddle
For greater than and less than symbol.
var string = '<><>';
string = string.replace(/[\<\>]/g,'*');
alert(string);
For special characters
var string = '<><>';
string = string.replace(/[&\/\\#,+()$~%.'":*?<>{}]/g,'_');
alert(string);
Insert the regular expression in the code before class
using System.Text.RegularExpressions;
below is the code for string replace using regex
string input = "Dot > Not Perls";
// Use Regex.Replace to replace the pattern in the input.
string output = Regex.Replace(input, "some string", ">");
source :
http://www.dotnetperls.com/regex-replace