Simple and fast solution
Well the simplest solution would be:
Number(frm.elements[i].value) * Number(frm.elements[i+1].value);
Since the quantity element always comes AFTER the checkbox element.
The JavaScript then becomes:
function total(frm)
{
var tot = 0;
for (var i = 0; i < frm.elements.length; i++) {
if (frm.elements[i].type == "checkbox") {
if (frm.elements[i].checked) tot +=
Number(frm.elements[i].value) * Number(frm.elements[i+1].value);
}
}
document.getElementById("totalDiv").firstChild.data = "£" + tot;
}
You can see this works here.
To guarantee that the total
div also gets updated when quantity is changed, you should add the onclick="total(this.form);"
event to the class="quantity"
input elements as well.
You can see how nicely this works here.
More advanced solution
Personally, I would use tabIndex
to group the checkbox
and quality
inputs.
For example, for the first product:
<td class="buttons">
<div>
<input tabindex="1" name="checkbox" type="checkbox" value="25" onclick="total(this.form);" />£25</div>
<input tabindex="1" name="quantity" min="0" max="5" type="number" class="quantity" value="1" onclick="total(this.form);"/>
</td>
As you can see, I have explicitly defined the tabIndex
and names
.
Now for the JavaScript, I now use:
function total(frm)
{
var tot = 0;
var checkboxes = document.forms[frm.id].elements["checkbox"];
var quants = document.forms[frm.id].elements["quantity"];
for (var i = 0; i < checkboxes.length; i++)
{
if (checkboxes[i].checked)
{
// if tabIndex correctly specified
if (checkboxes[i].tabIndex == quants[i].tabIndex)
// add to total
tot += Number(checkboxes[i].value) * Number(quants[i].value);
else
// notify of bug
alert('Bug in code: tabIndex of checkbox '+i+' is not the same as tabIndex quantity '+i);
}
}
document.getElementById("totalDiv").firstChild.data = "£" + tot;
}
By doing it this way you get the following advantages:
- Your HTML code makes more sense (input elements are grouped per
tabIndex
) - Your code is checked for bugs
- You are absolutely sure that you multiply the correct input elements
You can find this code in this jsFiddle.
Good luck! I hope this helps you out!
Update
To create a sort of checkout system, you could go over all the elements again and store them in a variable.
Then make sure that the form implements a function upon submit:
action="javascript:checkout()"
so in total:
<form action="javascript:checkout()" id="theForm">
Easiest way to create the message would be to use one variable like so:
function checkout()
{
var message = "";
var checkboxes = document.forms["theForm"].elements["checkbox"];
var quants = document.forms["theForm"].elements["quantity"];
for (var i = 0; i < checkboxes.length; i++)
{
if (checkboxes[i].checked)
{
switch(checkboxes[i].tabIndex)
{
case 1: message += "iPhone"; break;
case 2: message += "Screen"; break;
case 3: message += "Laptop"; break;
case 4: message += "Coffee"; break;
default: message += "";
}
message += " Quantity: " + Number(quants[i].value) + " Price: £" + Number(checkboxes[i].value) * Number(quants[i].value) + "\n";
}
}
message += "\nTotal: " + document.getElementById("totalDiv").firstChild.data;
alert(message);
}
You can find a working implementation of this here.
Fancy solution
Or if you would like to make it a little bit more fancy, you could do the following:
Add the following HTML:
HTML
<br><br>
<div id="checkout">
<table id="myTable" border="1">
<tr>
<td>Product</td>
<td>Quantity</td>
<td>Price</td>
</tr>
</table>
</div>
Add the following JavaScript function:
JavaScript
function checkout()
{
document.getElementById("checkout").innerHTML = '<table id="myTable" border="1"><tr><td><b>Product</b></td><td><b>Quantity</b></td><td><b>Price</b></td></tr></table>';
// Find a <table> element with id="myTable":
var table = document.getElementById("myTable");
var count = 0;
var max = 0;
var checkboxes = document.forms["theForm"].elements["checkbox"];
var quants = document.forms["theForm"].elements["quantity"];
for (var i = 0; i < checkboxes.length; i++)
{
if (checkboxes[i].checked)
{
switch(checkboxes[i].tabIndex)
{
case 1: message = "iPhone"; break;
case 2: message = "Screen"; break;
case 3: message = "Laptop"; break;
case 4: message = "Coffee"; break;
}
count += Number(quants[i].value);
max += 1;
// Create an empty <tr> element and add it to the table:
var row = table.insertRow(max);
// Insert new cells (<td> elements) at the 1st, 2nd and 3rd position
var cell1 = row.insertCell(0);
var cell2 = row.insertCell(1);
var cell3 = row.insertCell(2);
// Add some text to the new cells:
cell1.innerHTML = message;
cell2.innerHTML = Number(quants[i].value);
cell3.innerHTML = "£" + Number(checkboxes[i].value) * Number(quants[i].value);
}
}
// Calculate total
var row = table.insertRow(max+1);
var cell1 = row.insertCell(0);
var cell2 = row.insertCell(1);
var cell3 = row.insertCell(2);
cell1.innerHTML = "<b>Total</b>";
cell2.innerHTML = count;
cell3.innerHTML = document.getElementById("totalDiv").firstChild.data;
}
The result looks like this:
You can find the corresponding jsFiddle HERE.
Hope that helps you out!