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Javascript maths to poulate form

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oshjosh

oshjosh

Technical User
Mar 11, 2002
34
TH
I need to do some calculations in a form when a form loads so I would think onload is the best way to make this happen?

I have tried the following.

<BODY onLoad="document.forms[0].Price.value=( ((500) / (100)) * 17 + 500 );">

<input type="radio" value="" checked name="Price">

But it gives an error.

The idea is that when the page loads the radio buton has a value of 500 increased by 17%

However I would like to have 5 radio buttons that are increased by 17% 34% 51% 68% 85%

Any Ideas welcomed..

Thanks in advance

Rob
 
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If you know the value in advance - which clearly you do, as it is hardcoded in the onload tag you've shown - then why bother with JS at all? Why not just set the values of the inputs directly:

Code: 
<input type="radio" value="585" checked name="Price">

(585 == the result of the onload forumla you gave)

Hope this helps,
Dan
 
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Hi Dan

Thanks, I used the value 500 as an example to show a figure sorry.

I should have said this will be a dynamic page and 500 will be replaced by a value from a database.

Hnce the need for some javascript to give some alternative price options.

Cheers
Rob
 
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Have you tried using a function?

Code: 
<script language="JavaScript">
<!--
function getVal() {
    return (500 / 100) * 17 + 500;
}
//-->
</script>

<body onload="document.forms[0].Price.value=getVal();">

*cLFlaVA
----------------------------
Ham and Eggs walks into a bar and asks, "Can I have a beer please?"
The bartender replies, "I'm sorry, we don't serve breakfast.
 
Upvote 0 Downvote
Rob,

your code works for me in IE6, so all I can figure (short of you telling us what the error message is) is that you forgot to put in FORM tags.

'hope that helps.

--Dave
 
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Dave

You got it I never thought to put the form tags around it :)

How would I use this to have 5 radio buttons that are increased by 17% 34% 51% 68% 85% can I load more than one form IE

document.forms[0].
document.forms[1].
document.forms[2]. etc?

cLFlaVA

Can I just change the value of getFal() to getVal(1) etc?

<script language="JavaScript">
<!--
function getVal() {
return (500 / 100) * 17 + 500;
}
//-->
</script>

<body onload="document.forms[0].Price.value=getVal();">

Thanks in advance

Rob
 
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You probably don't want separate forms. You can only submit one form at a time and you probably want the radio buttons together as part of one group.

For economy and expandability, in a JavaScript-friendly environment, you can try something like this:

Code: 
<html>
<head>
<script>
var numOfRadios = 5;
var percentages = new Array(17,34,51,68,85);
function loadRadioVals()
{
 for(var i=0; i<numOfRadios; i++)
 {
  document.forms[0].elements["radio"+i].value = (500/100) * percentages[i] + 500; [b]//assuming this is the standard equation[/b]
 }
}
</script>
</head>
<body [b]onload='loadRadioVals()'[/b]>
<form>
<script>
for(var i=0; i<numOfRadios; i++)
 document.write("<input type='radio' name='radioGroup' id='radio"+i+"' />");
</script>
</form>
</body>
</html>

Let me know if you get what I did here.

--Dave
 
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...or, better yet:

Code: 
<html>
<head>
<script>
[b]//any future changes to number of radio buttons requires only you add or remove a value from the following array[/b]
var percentages = new Array(17,34,51,68,85);
var numOfRadios = percentages.length;
function loadRadioVals()
{
 for(var i=0; i<numOfRadios; i++)
 {
  var val = (500/100) * percentages[i] + 500;
  document.forms[0].elements["radio"+i].value = val;
  window["radioLabel"+i].innerText = val;
 }
}
</script>
</head>
<body onload='loadRadioVals()'>
<form>
<script>
for(var i=0; i<numOfRadios; i++)
{
 document.write("<input type='radio' name='radioGroup' id='radio"+i+"' />");
 document.write("<label id='radioLabel"+i+"' for='radio"+i+"'></label>");
}
</script>
</form>
</body>
</html>

--Dave
 
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Hi Dave

Works superb, when I see a script like this I can see how it works, I am just not advanced enough yet to actually write one on my own.

every time I post in this forum I get great help.

Cheers
Rob
 
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Hi Anyone (Dave)

have one last question, the script above works like a dream however some numbers have 6 decimal places after them, how would I limit this to 2 decimal places?

I have tried with some spipets I have seen to do this but it disables the funcyions so I am sure they are not going in the right place.

Cheers
Rob
 
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Try this:

[tt]Math.round(the_float_number * 100) / 100);[/tt]

*cLFlaVA
----------------------------
Ham and Eggs walks into a bar and asks, "Can I have a beer please?"
The bartender replies, "I'm sorry, we don't serve breakfast.
 
Upvote 0 Downvote
Hi cLFlava

Where would I put this in the above?

Cheers
Rob
 
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I guess like this:

[code[<html>
<head>
<script>
//any future changes to number of radio buttons requires only you add or remove a value from the following array
var percentages = new Array(17,34,51,68,85);
var numOfRadios = percentages.length;
function loadRadioVals()
{
for(var i=0; i<numOfRadios; i++)
{
var val = Math.round((500/100) * percentages + 500 * 100) / 100);
document.forms[0].elements["radio"+i].value = val;
window["radioLabel"+i].innerText = val;
}
}
</script>
</head>
<body onload='loadRadioVals()'>
<form>
<script>
for(var i=0; i<numOfRadios; i++)
{
document.write("<input type='radio' name='radioGroup' id='radio"+i+"' />");
document.write("<label id='radioLabel"+i+"' for='radio"+i+"'></label>");
}
</script>
</form>
</body>
</html>[/code]

*cLFlaVA
----------------------------
Ham and Eggs walks into a bar and asks, "Can I have a beer please?"
The bartender replies, "I'm sorry, we don't serve breakfast.
 
Upvote 0 Downvote
Works like dream.. thanks one last questio I have tried adding it into this and it just disables it..

<script>document.write( (($data[15]*100) / (2.54)) / 100 );</script> Again would like no more than 2 decimal places

$data[15] is a cariable replaced by the database

Cheers
Rob
 
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This looks like you're trying to use php.
Anyway, the same implementation would result:

[tt]<script>document.write(Math.round((((($data[15]*100) / 2.54) / 100) * 100) / 100));</script>[/tt]



*cLFlaVA
----------------------------
Ham and Eggs walks into a bar and asks, "Can I have a beer please?"
The bartender replies, "I'm sorry, we don't serve breakfast.
 
Upvote 0 Downvote
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