How to check there are only 2-4 characters [duplicate] - javascript

This question already has answers here:
Regular expression to match a dot
(7 answers)
Closed 2 years ago.
Using regex, I'm trying to check whether there's only 2-4 characters used after a .. At the moment, i got it working to detect when its less than 2 characters but after 4 characters, it still deems it as successful. How can I fix this? This is what I have written down:
/.[a-zA-Z]{2,4}$/

You need to escape the dot (.).
/\.[a-zA-Z]{2,4}$/

. is the control character in RegExp, you should to escape it:
/\.[a-zA-Z]{2,4}$/
And, to ignore case, add the i flag:
/\.[a-z]{2,4}$/i

Related

how to ignore removing a special character in a string [duplicate]

This question already has answers here:
Regex remove special characters
(4 answers)
Closed 2 years ago.
I am trying to strip all non numbers and this symbol * from a string.
An example would be
Input: "gdfgdf234dg54gf*23oP42"
Output: "23454*2342"
I have the following which removes everything apart from numbers. The issue is that it also removes the *. I am unsure how to ignore one character.
string.replace(/\D/g,'');
I am sure I will get ridiculed on here saying what else have I tried, but have searched for numerous answers on here.
Can anyone help?
Try [^\d*]
Regex Demo
console.log("gdfgdf234dg54gf*23oP42".replace(/[^\d*]/g,''))

JS: check if a single character is NOT a whitespace [duplicate]

This question already has answers here:
regex to match a single character that is anything but a space
(3 answers)
Closed 4 years ago.
How to check in JavaScript if the specified character is not a whitespace using regex only? Right now I am doing something like the code below with negation ! but I would like to avoid mixing of two things to avoid confusions.
if (!/\s/.test(character))
console.log('this is not a whitespace');
if (/\S/.test(character))
console.log('this is not a whitespace');
Use the negated set notation in the regex
/[^\s]/
That will match everything that isnt a whitespace.

RegEx validation Issue for allowing multiple whitespaces [duplicate]

This question already has answers here:
Learning Regular Expressions [closed]
(1 answer)
Match empty string, comma, hyphen or underscore once using regex
(2 answers)
Closed 4 years ago.
I have a requirement to do a field validation using regEx. The requirement is not to have any special characters. It is working for me for a single white space, but not for multiple white spaces. It does not work if there is a white space at the beginning. Can you please help me with this?
This is what I used:
^(\w+ ?)*$
You might be looking for
^[\w ]*$
The ^ and $ are anchors for the start/end of the string, the [...] is called a character class and would allow only [A-Za-z0-9_ ]. The * is a quantifier and means zero or more times, thus the expression would also allow an empty string. If this is not what you want, change it to + instead of the *. Please note that this would also allow a string with only spaces (it really depends on what you want).

JS: regex, $ end of input not able to use [duplicate]

This question already has answers here:
Validate phone number with JavaScript
(30 answers)
Closed 5 years ago.
console.log(/\d+?\d+?\d+?-\d+?\d+?\d+?-\d+?\d+?\d+?\d+?$/.test("555-555-55539"));
Answer --> true
I was looking for false, i am validating phone numbers. e.g. 555-555-5555 is a correct response([0-9])
I am a newbie to regex, can anyone explain what i am doing wrong here?
How about this.
console.log(/\d{3}-\d{3}-\d{4}$/.test("555-555-55539"));
You used wrong quantifiers in your regex. You made them lazy (+?), but it will still match all characters until the next character from regex is found. In case of your last quantifier (just before $) it will match all digits until the end of string is found. Hence it matches not only one digit but all of them. Same thing happens before each hyphen (555555555-5555-555555555 is valid for your regex).

How to use a slash in javascript RegExp [duplicate]

This question already has answers here:
Matching a Forward Slash with a regex
(9 answers)
Closed 6 years ago.
How do I make a Slash able to be used in this Metachar String:
/#(\w+)\b/gi
That is supposed to find the "Text"(#text) This is a test #Text I agree
And it does. But now I wan't the same thing for somthing that uses a
/
You need to escape the slash so it is not interpreted as denoting special meaning. Escaping means prefixing with a backslash, so you just need two together. Adapting your existing example:
/#([\w\/]+)\b/gi
You're now allowing alphanumeric and slash characters (hence the need for a "range" of characters, denoted by square brackets.)
This one will do it: Try:(will match /Text)
/\/(\w+)\b/gi

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