Question

I’m trying to make a textbox give a message to the user if they enter the number 1, in it for example. It should then show a pop up saying that this product is only available in multiples of 5.

Here is my code.

<script language="JavaScript">
function chk_boxquantity(inField) {
    step3_submit_disable();

    var fVal = inField.value;
    var fBoxQuantity = 5;

    if (mod(fVal, fBoxQuantity) != 5) {
        alert('This product is only available in multiples of '+fBoxQuantity);
        inField.value = Math.ceil(fVal/fBoxQuantity)*fBoxQuantity;
        setTimeout(function() {
            inField.focus();inField.select();gAutoBlur = false;
        }, 10);
    }

    step3_submit_enable();
}
</script>

Here is the text field.

<input type="text" onkeypress="return handleEnter(this, event);" 
onblur="chk_boxquantity(this);" name="qty[<?php echo $card['id']; ?>]" 
size="3" />

So wherever, the user clicks, it will pop up with the message. This is not working though, any ideas why not?

Thanks,

Jonah

Answer 1

Change your Code From mod() to % operator DEMO

FROM

 if (mod(fVal, fBoxQuantity) != 5)

TO

  if ((fVal % fBoxQuantity) != 0) 

Complete Function may look like

function chk_boxquantity(inField)
{
    var fVal = inField.value;
    var fBoxQuantity = 5;

    if ((fVal % fBoxQuantity) !== 0)
    {
     alert('This product is only available in multiples of '+fBoxQuantity); 
      inField.value = Math.ceil(fVal/fBoxQuantity)*fBoxQuantity ;
    }

}

Only required code is shown.