Question

I’m using jQuery as the validation tool for all of my forms and I have a request to limit the length of the inputs on one field to 8, 12, or 13 characters only. Now, I’m already doing minlength: 8, and maxlength: 13 to take care of the upper and lower limits but haven’t figured out how to limit the entry to exactly one of the three lengths.

Answer 1

You could add a custom validation method.
Here is some rough code to get you started:

jQuery.validator.addMethod("specific_lengths", function(value, element, param) {
   if (this.optional(element)) return;

   for (var i = 0; i < param.length; i++){
       if (this.getLength($.trim(value), element) == param[i]) 
           return true;
   }

   return false;              
});

You could then hook up the validation like this:

jQuery("#myform").validate({
  rules: {
    myField: {required: true,
              specific_lengths: [8, 12, 13]
             },
  ...