Hello,

I don't know javascript very but I am trying to modify an order form. I would like the checkbox prices to be multiplied by the total select option amounts. I want that price to update if/when the select options change.

Example:
Select totals of Item1 + Item2 * Item 3 's price
If Item 3 = 50cts, 50cts would be added for each item amount selected under Item 1 and Item 2.

How would that be done?

I did see an old post which used itemTotal('1') but I believes that that gives the number an alpha value.

I would appreciate any help.


HTML code
Code:
<html>
<script type="text/javascript" src="orderform03.js"></script>

<script type="text/javascript">
//<![CDATA[
window.onload = setupScripts;
function setupScripts()
{
   var anOrder1 = new OrderForm();
   var anOrder2 = new OrderForm('a_');
   var anOrder3 = new OrderForm('b_');
   var anOrder4 = new OrderForm('c_', 2);
}
//]]>
</script>

<form id="frmOrder">
<table>
   <tr>
      
      <td>Item 1</td>
      <td>$<span id="txtPrice0">10</span></td>
      <td>
         <select id="sel0">
            <option value="val0">0</option>
            <option value="val1">1</option>

            <option value="val2">2</option>
            <option value="val3">3</option>
         </select>
      </td>
   </tr>
   <tr>
      
      <td>Item 2</td>
      <td>$<span id="txtPrice1">10</span></td>
      <td>
         <select id="sel1">
            <option value="val0">0</option>
            <option value="val1">1</option>

            <option value="val2">2</option>
            <option value="val3">3</option>
         </select>
      </td>
   </tr>

   <tr>
      
<td>Item 3</td>
      <td>$<span id="txtPrice2">20</span></td>
      <td><input type="checkbox" id="chk1" /></td>
      
         
      </td>
   </tr>
</table>
<p>
Total:
<input type="text" id="txtTotal" size="8" />
</p>
</form>
</html>

js file
===================================
// mredkj.com
// OrderForm.js - v0.3
// v0.3 - 2006-04-09
// v0.2 - 2006-04-08
// v0.1 - 2006-04-06

function OrderForm(prefix, firstChoice) {

this.prefix = prefix ? prefix : '';

// ****************************
// Configure here
// ****************************
// names - Set these according to how the html ids are set
this.FORM_NAME = this.prefix + 'frmOrder';
this.BTN_TOTAL = this.prefix + 'btnTotal';
this.TXT_OUT = this.prefix + 'txtTotal';

// partial names - Set these according to how the html ids are set
this.CHK = this.prefix + 'chk';
this.SEL = this.prefix + 'sel';
this.PRICE = this.prefix + 'txtPrice';

// if the drop down has the first choice after index 1
// this is used when checking or unchecking a checkbox
this.firstChoice = firstChoice ? firstChoice : 1;
// ****************************

// form
this.frm = document.getElementById(this.FORM_NAME);

// checkboxes
this.chkReg = new RegExp(this.CHK + '([0-9]+)');
this.getCheck = function(chkId) {
return document.getElementById(this.CHK + chkId);
};

// selects
this.selReg = new RegExp(this.SEL + '([0-9]+)');
this.getSelect = function(selId) {
return document.getElementById(this.SEL + selId);
};

// price spans
this.priceReg = new RegExp(this.PRICE + '([0-9]+)');

// text output
this.txtOut = document.getElementById(this.TXT_OUT);

// button
this.btnTotal = document.getElementById(this.BTN_TOTAL);

// price array
this.prices = new Array();

var o = this;
this.getCheckEvent = function() {
return function() {
o.checkRetotal(o, this);
};
};

this.getSelectEvent = function() {
return function() {
o.totalCost(o);
};
};

this.getBtnEvent = function() {
return function() {
o.totalCost(o);
};
};

/*
* Calculate the cost
*
* Required:
* Span tags around the prices with IDs formatted
* so each item's numbers correspond its select elements and input checkboxes.
*/
this.totalCost = function(orderObj) {
var spanObj = orderObj.frm.getElementsByTagName('span');
var total = 0.0;
for (var i=0; i<spanObj.length; i++) {
var regResult = orderObj.priceReg.exec(spanObj[i].id);
if (regResult) {
var itemNum = regResult[1];
var chkObj = orderObj.getCheck(itemNum);
var selObj = orderObj.getSelect(itemNum);
var price = orderObj.prices[itemNum];
var quantity = 0;
if (selObj) {
quantity = parseFloat(selObj.options[selObj.selectedIndex].text);
quantity = isNaN(quantity) ? 0 : quantity;
if (chkObj) chkObj.checked = quantity;
} else if (chkObj) {
quantity = chkObj.checked ? 1 : 0;
}
total += quantity * price;
}
}
orderObj.txtOut.value = total;
};

/*
* Handle clicks on the checkboxes
*
* Required:
* The corresponding select elements and input checkboxes need to be numbered the same
*
*/
this.checkRetotal = function(orderObj, obj) {
var regResult = orderObj.chkReg.exec(obj.id);
if (regResult) {
var optObj = orderObj.getSelect(regResult[1]);
if (optObj) {
if (obj.checked) {
optObj.selectedIndex = orderObj.firstChoice;
} else {
optObj.selectedIndex = 0;
}
}
orderObj.totalCost(orderObj);
}
};

/*
* Set up events
*/
this.setEvents = function(orderObj) {
var spanObj = orderObj.frm.getElementsByTagName('span');
for (var i=0; i<spanObj.length; i++) {
var regResult = orderObj.priceReg.exec(spanObj[i].id);
if (regResult) {
var itemNum = regResult[1];
var chkObj = orderObj.getCheck(itemNum);
var selObj = orderObj.getSelect(itemNum);
if (chkObj) {
chkObj.onclick = orderObj.getCheckEvent();
}
if (selObj) {
selObj.onchange = orderObj.getSelectEvent();
}
if (orderObj.btnTotal) {
orderObj.btnTotal.onclick = orderObj.getBtnEvent();
}
}
}
};
this.setEvents(this);

/*
*
* Grab the prices from the html
* Required:
* Prices should be wrapped in span tags, numbers only.
*/
this.grabPrices = function(orderObj) {
var spanObj = orderObj.frm.getElementsByTagName('span');
for (var i=0; i<spanObj.length; i++) {
if (orderObj.priceReg.test(spanObj[i].id)) {
var regResult = orderObj.priceReg.exec(spanObj[i].id);
if (regResult) {
orderObj.prices[regResult[1]] = parseFloat(spanObj[i].innerHTML);
}
}
}
};
this.grabPrices(this);

}