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 validate your input value using onBlur event on TextInput You can apply your regex or check conditions on this event.

Like this:

 {
        //Conditions or Regex
      }
/>

In your case, 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);
};

Text Input Code:

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