CODEWITHSUNDEEP
javascriptregex
Shourya Shikhar
Shourya Shikhar

Reputation: 1524

regex: match string where n number of alphabets mandatory and optional numerics and underscore

I am trying to validate a username field like this:

  1. 6 alphabets mandatory
  2. Might contain any number of numericals
  3. Might contain any number of underscores

For example: abcdef, abc9def, _testaa, __test_aa_, hello_h_9, _9helloa, 9a8v6f_aaa All these should match, that is, the number of alphabets should be more than n numbers (here 6) in the whole string, and _ and numerics can be present anywhere.

I have this regex: [\d\_]*[a-zA-Z]{6,}[\d\_]* It matches strings like: _965hellof But doesn't match strings like: ede_96hek

I also have tried this regex: ^(?:_?)(?:[a-z0-9]?)[a-z]{6,}(?:_?)(?:[a-z0-9])*$ Even this fails to match.

Upvotes: 3

Views: 85

Answers (3)

blhsing
blhsing

Reputation: 106883

You can do:

^\w*(?:[A-Za-z]\w*){6,}$

Demo: https://regex101.com/r/yoGr82/1

Upvotes: 2

Mina
Mina

Reputation: 17394

One solution is splitting the str and on each character checking if it's an alphabet with .filter(v => isNaN(v) && v !== '_') and then get the length to check if it's more than 6 alphabets.

const checkValidation = (str) => {
  return /[\d\_a-z]/gi.test(str) && str.split('').filter(v => isNaN(v) && v !== '_').length >= 6
}

console.log(checkValidation('something_123'))
console.log(checkValidation('12somtg1'))
console.log(checkValidation('123some12tg'))
console.log(checkValidation('123some12_'))
console.log(checkValidation('_965hellof'))
console.log(checkValidation('ede_96hek'))

Upvotes: 2

Chris Maurer
Chris Maurer

Reputation: 2580

You need to use a lookahead like this:

/^(?=[^A-Za-z]*([A-Za-z][^A-Za-z]*){6}$)\w+$/

This is in two parts, the long part verifies there are exactly 6 alphabetic characters present without moving the scanners cursor position. Then the \w+ says all the characters must be alphanumeric or underscore. The ^ & $ ensure the entire string conforms.

Upvotes: 2

Related Questions