How to validate TextInput values in react native?

Question

for example, While entering an email in the TextInput, it should validate and display the error message. where the entered email is valid or not

Answer 1

You can use a regex to check if the mail entered is valid.

Regex function

validateEmail = (email) => {
  var re = /^(([^<>()\[\]\\.,;:\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,}))$/;
    return re.test(email);
};

Submit text input function

onSubmit = () => {
if (!this.validateEmail(this.state.text_input_email)) {
  // not a valid email
} else {
  // valid email
}