I have created a form validation plugin just like jQuery Validation Plugin

But I have no idea how to wait for remote validations like check for duplicate usernames

jQuery Validation Plugin:

var form = $('form');

form.validate();

if (form.valid()) {
  //Do something if the form is valid
}

My Validation Plugin:

var form = $('form');

if (await form.valid()) {
  //Do something if the form is valid
}

I don't like to use async and await operators and I would like to know how the jQuery Validation Plugin does this without using async and await operators