What does this.optional(element) do when adding a jQuery validation method?

Question

Please see the documentation:
https://jqueryvalidation.org/jQuery.validator.addMethod/

I wonder what this.optional(element) does. I created two fo

Answer 1

OK... so in your examples, the field is never blank in either form. Either it has a placeholder value, or an attempt at an email address. The whole point of this.optional(element) is to immediately return true if the element is blank AND it is not required.

So if you had these two methods:

jQuery.validator.addMethod("BOB", function (value, element) {
    return this.optional(element) || 
        element.value === 'BOB';
}, 'You did not enter BOB');

jQuery.validator.addMethod("mustbeBOB", function (value, element) {
    return element.value === 'BOB';
}, 'You did not enter BOB');

Adding a class of BOB required would be the same as entering a class of mustbeBOB. Compare that to having a class of BOB which would allow for a blank or "BOB", vs a class of mustbeBOB which will only pass validation with a value of BOB, blank would fail. Does that make more sense?