Question

I try to get this code to work with the 3 input fields, but it works only with the first :

<form>  
<p><input id="qty" type="text" maxlength="1"  /></p>
<p><input id="qty" name="text" type="text"  /></p>
<p><input id="qty" name="text2" type="text" /></p>
</form>

<script type="text/javascript">

$("#qty").change(function(e) {
    if(this.value != '3' && this.value != '6' && this.value != '9') {
        this.value = 0;         
        alert('You can buy only 3, 6, or 9 pieces fromn this product');
    } });

</script>

What can be my error ?

Answer 1

You cannot have 3 things with the same ID try using classes instead:

<form>  
<p><input class="qty" type="text" maxlength="1"  /></p>
<p><input class="qty" name="text" type="text"  /></p>
<p><input class="qty" name="text2" type="text" /></p>
</form>

<script type="text/javascript">

$(".qty").change(function(e) {
    if(this.value != '3' && this.value != '6' && this.value != '9') {
        this.value = 0;         
        alert('You can buy only 3, 6, or 9 pieces fromn this product');
    } });

</script>