Change text field value upon checkbox clicking

guvenck · 01-20-2006, 03:54 PM

Hi,

I have a text field with a number value in it. Let's call it CreditsLeft.
Below, I have checkboxes, the visitor checks these boxes and selects some services.

1- When a checkbox is checked, I want to decrease (or increase when unchecked) the CreditsLeft value by one.

2- What if I want a service decrease by one and another service by 2 or another 3?

How can I do that?

Thanks,
Guvenc

vwphillips · 01-20-2006, 04:03 PM

Code:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
    "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>
  <title></title>
<script language="JavaScript" type="text/javascript">
<!--

function Cal(obj,id){
 var tar=document.getElementById(id);
 if (obj.checked){
  tar.value=parseFloat(tar.value)+parseFloat(obj.value)
 }
 else {
  tar.value=parseFloat(tar.value)-parseFloat(obj.value)
 }
}
//-->
</script></head>

<body>
<input id="fred" value="100" ><br>
<input type="checkbox" name="" value="20" onclick="Cal(this,'fred');">
<input type="checkbox" name="" value="30" onclick="Cal(this,'fred');">
<input type="checkbox" name="" value="2" onclick="Cal(this,'fred');">
</body>

</html>

guvenck · 01-20-2006, 07:40 PM

That solves the problem. Many thanks for this quick reply. You are great!

guvenck · 01-21-2006, 02:39 PM

Want to add some control over this:
If the credits is below zero, I want to alert the visitor.

Following code works as I want, but it displays -1 before sending the alert. How can I prevent the -1 from being displayed?

Quote:

vwphillips · 01-21-2006, 04:09 PM

Code:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
    "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>
  <title></title>
<script language="JavaScript" type="text/javascript">
<!--

function Cal(obj,id){
 var tar=document.getElementById(id);
 var val=0
 if (obj.checked){
  val=parseFloat(tar.value)+parseFloat(obj.value);
 }
 else {
  val=parseFloat(tar.value)-parseFloat(obj.value);
 }
 if (val<0){
  alert('insufficent funds');
  obj.checked=false;
  return;
 }
 tar.value=val
}
//-->
</script></head>

<body>
Want to add some control over this:
If the credits is below zero, I want to alert the visitor.

Following code works as I want, but it displays -1 before sending the alert. How can I prevent the -1 from being displayed?
<input id="fred" value="100" ><br>
<input type="checkbox" name="" value="20" onclick="Cal(this,'fred');">
<input type="checkbox" name="" value="-130" onclick="Cal(this,'fred');">
<input type="checkbox" name="" value="2" onclick="Cal(this,'fred');">
</body>

</html>

guvenck · 01-21-2006, 05:57 PM

How many times do I have to thank you?

guvenck · 01-25-2006, 09:48 PM

I have a textbox that is enabled upon clicking a checkbox.
If I use the method above, the credits are calculated even if the visitor does not type anything into the text field. I need the credits to be decreased by 1 if the visitor types anything into the text field. What should I do?

Quote:

Quote:

<input type="checkbox" name="bs" value="1" onClick="javascript:Cal(this,'fred'); toggleCheckbox2();">
before 
<input type="text" class="inputbox" name="bscustom" size="2" maxlength="2" value="<?php echo "$value"; ?>">
days 