Add plus & minus buttons with input type text

add-plus-minus-buttons-with-input.html

<style>
#myform {
    text-align: center;
    padding: 5px;
    border: 1px dotted #ccc;
    margin: 2%;
}
.qty {
    width: 40px;
    height: 25px;
    text-align: center;
}
input.qtyplus { width:25px; height:25px;}
input.qtyminus { width:25px; height:25px;}
</style>
<form id='myform' method='POST' action='#'>
    <input type='button' value='-' class='qtyminus' field='quantity' />
    <input type='text' name='quantity' value='0' class='qty' />
    <input type='button' value='+' class='qtyplus' field='quantity' />
</form>
<script src="https://code.jquery.com/jquery-3.2.1.min.js" integrity="sha256-hwg4gsxgFZhOsEEamdOYGBf13FyQuiTwlAQgxVSNgt4=" crossorigin="anonymous"></script>
<script>
jQuery(document).ready(function(){
    // This button will increment the value
    $('.qtyplus').click(function(e){
        // Stop acting like a button
        e.preventDefault();
        // Get the field name
        fieldName = $(this).attr('field');
        // Get its current value
        var currentVal = parseInt($('input[name='+fieldName+']').val());
        // If is not undefined
        if (!isNaN(currentVal)) {
            // Increment
            $('input[name='+fieldName+']').val(currentVal + 1);
        } else {
            // Otherwise put a 0 there
            $('input[name='+fieldName+']').val(0);
        }
    });
    // This button will decrement the value till 0
    $(".qtyminus").click(function(e) {
        // Stop acting like a button
        e.preventDefault();
        // Get the field name
        fieldName = $(this).attr('field');
        // Get its current value
        var currentVal = parseInt($('input[name='+fieldName+']').val());
        // If it isn't undefined or its greater than 0
        if (!isNaN(currentVal) && currentVal > 0) {
            // Decrement one
            $('input[name='+fieldName+']').val(currentVal - 1);
        } else {
            // Otherwise put a 0 there
            $('input[name='+fieldName+']').val(0);
        }
    });
});

</script>