change value for calculation - help

[cassbiz]

I may be in the wrong forum so Ronald don't shoot :)

In my code I have an option box to choose a number - works fine. I want to carry over the new value to another field to do a recalculation.

Primarily the field "$preis1" to change with the javascript.

Here is the code.

        <script type="text/javascript">
                <!--
                function perscount()
                {
                if (document.daten.pers.value==1){
                document.daten.preis.value = document.daten.preis1.value;}
                if (document.daten.pers.value==2){
                document.daten.preis.value = document.daten.preis2.value;}
                if (document.daten.pers.value==3){
                document.daten.preis.value = document.daten.preis3.value;}
                if (document.daten.pers.value==4){
                document.daten.preis.value = "";}
                }
                        //-->
        </script>
<?
$zdaten = getzimmer();
$i=0;
while  (count ($zdaten) >= $i)
{
        $i++;
        if ($zdaten[$i][1]==$zimmer)
        {
                $preis1=$zdaten[$i][2];
                $preis2=$zdaten[$i][3];
                $preis3=$zdaten[$i][4];
                $preis4=$zdaten[$i][5];
                $preis5=$zdaten[$i][6];
        }
}
?>
<input type="hidden" name="preis1" value=<? echo "'$preis1'"?>>
<input type="Hidden" name="preis2" value=<? echo "'$preis2'"?>>
<input type="Hidden" name="preis3" value=<? echo "'$preis3'"?>>
<input type="Hidden" name="preis4" value=<? echo "'$preis4'"?>>
<input type="Hidden" name="preis5" value=<? echo "'$preis5'"?>>

 <!--took out the blah blah -->


        <tr id="tr2">
                <td align = "center" class="t1">
                        <? echo $t_forms['pers'] ?> <br>
                        <select name="pers" size="1" onChange="perscount()">
                        <option <? if ($pers==1) echo 'selected'; ?>>1</option>
                        <option <? if ($pers==2) echo 'selected'; ?>>2</option>
                        <option <? if ($pers==3) echo 'selected'; ?>>3</option>
                        <option <? if ($pers==4) echo 'selected'; ?>>4</option>
                </td>
        </tr>
        <tr id="tr2">
                <td class="t1">
<? echo $t_forms['price_day'] ?> <input name="preis" size="20" class="t1" maxlength="20" value=<?echo "'$preis1'" ?> >
<?
        $nächte1 = ($abdatum-$andatum)/86400;
        $nächte2 = $nächte1 + 0.5;
        $nächte = round($nächte2);

<!-- I would like to change the value of $pries1 to the new value given by the javascript to do the calculation. -->

        $sum1 = $nächte * $preis1;
        $sum = number_format($sum1, 2);
        $tax1 = $t_global['tax'];
        $tax2 = $sum1 * ($tax1 * .01);
        $tax = number_format($tax2, 2);
        $tot1 = $sum + $tax;
        $tot2 = $sum1 + $tax2;
        $tot = number_format($tot2, 2);
?>
                </td>
        <tr id="tr2">
                <td class="t1" colspan="2">
                        <? echo "{$t_forms['count']} : $nächte"; ?>
                </td>
        <tr id="tr2">
                <td class="t1" colspan="2">
                        <? echo "{$t_forms['sum']} = {$t_global['currency']} $sum"; ?>
                </td>
        <tr id="tr2">
                <td class="t1" colspan="2">
                        <? echo "{$t_forms['tax']} {$t_global['tax']}% = {$t_global['currency']} $tax"; ?>
                </td>
        <tr id="tr2">
                <td class="t1" colspan="2">
                        <? echo "{$t_forms['total']} {$t_global['currency']} $tot"; ?>
                </td>
        </tr>

Is there a real easy way to put that calculation into JavaScript so that it will change per the 'OnChange'? If so, I don't know very much about javascript.

Thanks in Advance

[ronverdonk]

No, there is no easy way. JavaScript runs client-side and PHP at the server. (the code being in one script does not mean that they run on the same machine!). So you'll have to set up a communication between client and server. There are ways to do that, but you'll have to redesign your script for that.

You could start at the JS side and then put a httpRequest call to the backend PHP with the price passed. Only then could the php script execute.

I wonder if that is what you meant by an easy way? If so, you can pursue this using httpRequest (or Ajax). Good luck!

Ronald :cool:

[cassbiz]

Do you know of a tutorial or possibly helping me out in changing the calculation over to js.

The value is not stored in a db it is only a visual on the screen and for print.