auto numbering based on year and value in Laravel 5.6 - php

Question

This for my dropdownlist and format for auto numbering
and if someone choose NK/W will get No.Reg :
001/NK/W/2018, 002/NK/W/2018, 003/NK/W/2018
And if someone choose NK/S will get No. Reg 001/NK/S/2018.
If years change, the auto numbering will reset to 001 again

Answer 1

The solution here has more to do with javascript than Laravel or PHP for instance.
Check this out
https://jsfiddle.net/j6znavy9/
<p>
Reg No: Auto/
<select id="mySelect">
<option selected disabled>Select an Option</option>
<option value="NK/W">NK/W</option>
<option value="NK/S">NK/S</option>
<option value="MM/A">MM/A</option>
</select>
Year: *
<select id="yearSelect">
<option selected disabled>Select a Year</option>
<option value="2018">2018</option>
<option value="2019">2019</option>
<option value="2020">2020</option>
</select>
</p>
<script>
$(document).ready(function() {
function pad(number, size) {
var s = String(number);
while (s.length < (size || 2)) {s = "0" + s;}
return s;
}
var year, mySelect, auto = 1;
$('#yearSelect').on('change', function(){
year = $(this).val();
auto = 1;
});
$('#mySelect').on('change', function(){
if( year === null || year === undefined ) {
alert('year is not defined!');
} else {
alert('Reg No: ' + pad(auto, 3) + '/' + $(this).val() + '/' + year);
auto++;
}
})
});
</script>