How can I implement custom validation in different frameworks?

How can I implement custom validation in different frameworks?

You can implement custom validation by creating validation functions specific to each framework's requirements. Which framework are you using?

I'm using React. Any specific examples?

In React, you can create a custom validation function and use it in your form handling. For instance, you can validate an email input by checking its format.

What about Angular? Is it similar?

In Angular, you can create custom validators by implementing the ValidatorFn interface. You can then apply these validators to your form controls.

Can you give me a code snippet for that?

Sure! Here's a simple example of a custom email validator in Angular:

import { AbstractControl, ValidatorFn } from '@angular/forms';

export function emailValidator(): ValidatorFn {
  return (control: AbstractControl): { [key: string]: any } | null => {
    const isValid = /^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/.test(control.value);
    return isValid ? null : { 'invalidEmail': { value: control.value } };
  };
}