How to show alert for duplicated value of textbox

Question

I have multiple input fields with different values. I can edit them but cannot be empty (if empty show an alert). When I am editing it to new values, if the new value matches with any of the other inputs values, I need an alert that you cannot use this.

HTML

<input type="text" class="selector" value="new">
<input type="text" class="selector" value="old">
<input type="text" class="selector" value="newest">
<input type="text" class="selector" value="oldest">
<input type="text" class="selector" value="older">

JavaScript

$('.selector').change(function () {
    alert();
});

Fiddle here

Answer 1

Updated Fiddle.

You can refresh the value attribute using $(this).attr('value', $(this).val()); first, then check if there's any other field with class selector has the same value using value selector $('.selector[value="' + current_value + '"]').length.

Hope this helps.

---

$('body').on('blur', '.selector', function () {
    $(this).attr('value', $(this).val());

    if ($('.selector[value="' + $(this).val() + '"]').length > 1 ) {
        $(this).focus();
        alert('You cannot use this');
    }else if($(this).val().length == 0) {
        alert('Empty value not accepted');
    }
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type="text" class="selector" value="new">
<input type="text" class="selector" value="old">
<input type="text" class="selector" value="newest">
<input type="text" class="selector" value="oldest">
<input type="text" class="selector" value="older">

Answer 2

Try this Code:

$('.selector').on('blur',function () {
   if ($('.selector[value="'+$(this).val()+'"]').not($(this)).length > 0 || current_value.length == 0 ) {
    alert('duplicate value');
   }
});

http://jsfiddle.net/0c0qep6y/12/