Please Help!!! - I'm having trouble with changing the value of an <input>

lifeform posted this at 21:24 — 7th September 1999.

They have: 7 posts

Joined: Aug 1999

here's my problem... I want to create several <select> menus, having each option inside them assigned an integer value, with an <input> that contains the total of all of the selected options.... here's example code if anyone can help

<html>
<head><title></title>
<script language='javascript'>
var drivevalue =0;
var monitorvalue = 0;

function compute(obj) {
obj.expr.value = (drivevalue + monitorvalue);
}

function calculate(obj) {
drivevalue = obj.drivelist.selectedIndex.value;
monitorvalue = obj.monitorlist.selectedIndex.value;
compute(obj);
}

</script>
<body bgcolor='#ffffff' text='#000000' link='#800000' vlink='#800000'>
<form>
<select name="drivelist" size="1">
<option value="100">Big Drive</option>
<option value="50">Small Drive</option>
</select>
<select name="monitorlist" size="1">
<option value="200">Big Monitor</option>
<option value="150">Small Monitor</option>
</select>
<input type="button" value="compute" onClick="calculate(this.form)">
<INPUT TYPE=text NAME="expr" SIZE=20>
</form>
</body>
</html>

thanks for any help....

----------
Best Wishes and Tuna Fishes

lifeform posted this at 21:25 — 7th September 1999.

They have: 7 posts

Joined: Aug 1999

hey thanks!!! I got it to work a different way... but only for I.E. 5.0.... if ya wanna see it, it's
http://www3.sympatico.ca/lifeform7
it's in the products section under customize a system....

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Best Wishes and Tuna Fishes

elara posted this at 23:52 — 7th September 1999.

They have: 112 posts

Joined: Apr 1999

lifeform,
You have missed two important things in the script.
First of all, the options value should be accessed like this:
obj.drivelist.options[obj.drivelist.selectedIndex].value
Secondly, the value obtained from the options are strings, so you need to convert them into integers with the parseInt() function.
The modified script is at below.

<html>
<head><title></title>
<script language='javascript'>
var drivevalue =0;
var monitorvalue = 0;

function compute(obj) {
obj.expr.value = (drivevalue + monitorvalue);
}

function calculate(obj) {
drivevalue = parseInt(obj.drivelist.options[obj.drivelist.selectedIndex].value);
monitorvalue = parseInt(obj.monitorlist.options[obj.monitorlist.selectedIndex].value);
compute(obj);
}

Hope this helps...
Later.

Joe Thong