JavaScript Form Validation

We are seeking a skilled JavaScript developer to implement form validation using JavaScript. The task involves ensuring that both name and surname in the form are filled, if not - then a message must show up with a hint for the user. Also, there must be international phone number mask with flags in UI, so user can choose his phone number country code and enter the number, phone number must be validated. Also, there must be an email validation. I need this script to be re-usable and simple to change / mantain, because I will use it for different landing pages. Also, there must be variable or variables in the code, using which I can control the form content: name and surname or full name only, email included or not. Please, name any yellow fruit as a start of your cover letter, so that I know you are not bot and share how much time do you need to get this done. Example HTML with the basic form structure will be provided.