How to check if input in input field has alphabets only in express-validator

.isAlpha() method description from validator.js documentation (express-validator is also a wrapper for validation functions of this module):

check if the string contains only letters (a-zA-Z)

Your string John Doe contains a whitespace, that’s why validation is not succesfull.

Your validation chain can be this one:

req.check('name')
   .isLength({min:3}).withMessage('Name must be of 3 characters long.')
   .matches(/^[A-Za-z\s]+$/).withMessage('Name must be alphabetic.')

.isAlpha() is replaced with matches(). Validation is successful when name is a string with 3 characters and more (alphabetic characters or whitespaces only).

Source: validator.js validators

Reference Link – https://stackoverflow.com/questions/58475407/how-to-check-if-input-in-input-field-has-alphabets-only-in-express-validator