Form validation regular expressions

let regEx

// At least one letter (any case)
regEx = /(?=.*[a-zA-Z])/

// At least one letter and one number
regEx = /(?=.*\d)(?=.*[a-zA-Z])/

// At least one uppercase letter, one lowercase letter and one number
regEx = /(?=.*\d)(?=.*[a-z])(?=.*[A-Z])/

// At least one uppercase letter, one lowercase letter, one number and one special character (symbol)
regEx = /(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?=.*\W)/

// Email regular expression pattern
regEx = /^(([^<>()\[\]\\.,;:\s@"]+(\.[^<>()\[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/