html form 2 fields unique values required - php

Question

I have a html form which has around 10 fields. 2 of those fields must have unique values.
So if I've got:
Name
Date of Birth
Email Address
Current City
Phone Number
Favourite City << Must be unique compared to City Born
City Born << Must be unique compared to Favourite City
Favourite Colour
Favourite Flower
Favourite Animal
I've found the below for validation, but that applies to all form fields. I just need to apply the 'unique' requirement to these two fields...it'd be okay for 'Favourite City' and 'Current City' to have the same values.
Thanks.
var frm = document.querySelector('form.classesName');
var inputs = frm.querySelectorAll('input[type=text]');
frm.addEventListener('submit', function(e) {
e.preventDefault();
var classArr = [];
for(var i = 0; i < inputs.length; i++) {
if(classArr.indexOf(inputs[i].value) != -1) {
inputs[i].style.backgroundColor = "red";
return false;
}
else
classArr.push(inputs[i].value);
}
frm.submit();
});
for(var j = 0; j < inputs.length; j++) {
inputs[j].addEventListener('focus', function() {
this.style.backgroundColor = "white";
});
}
https://jsfiddle.net/samuraii/70nkhthc/

Answer 1

Going off of the JavaScript you posted, and making some assumptions regarding the HTML make up of your form, would something like this work out?
var frm = document.querySelector('form.classesName');
frm.addEventListener('submit', function(e) {
e.preventDefault();
var favoriteCity = document.querySelector('input[name="favoriteCity"]');
var cityBorn = document.querySelector('input[name="cityBorn"]');
if ( favoriteCity.value === cityBorn.value ) {
alert("The City Where One Was Born Can't Be Their Favorite City... ?");
return false;
}
frm.submit();
});
<form class='classesName'>
<input type='text' name='favoriteCity' placeholder='Favorite City'>
<input type='text' name='cityBorn' placeholder='City Born'>
<input type='submit' value'Submit Form'>
</form>