Regex to match hashtag character with string format in javascript

Question

I need a Regex to match a certain string format in javascript,

A hashtag symbol '#' has to be first and last character , There must be strings between these two characters,

If the string is more than one there must be two hashtag '##' symbol between each of them there is no limit to strings number.

Ex.

1. #string1##string2##string3##...##string4#

2. #string1#

3. #string##string2#

Answer 1

You can check the below regex with this pattern

#[^\#]+# : All characters (except # ) between ##

(#[^\#]+#)+ : At least a string matched the pattern

^ and $ : Start and end of regex

 const checkRegex = (value) => { const regex = /^(#[^\#]+#)+$/ return regex.test(value) } console.log(checkRegex("#test")) //false console.log(checkRegex("#test#")) //true console.log(checkRegex("#test##")) //false console.log(checkRegex("#test##test#")) //true console.log(checkRegex("#test##test##")) //false

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