Javascript calculations

Encenta.com · 08-15-2007, 02:17 PM

Hi, I'm looking for a way to calculate a set of dropdown lists. Eg:

HTML Code:

<select name="dd[0]">
<option value="+21">Value</option>
<option value="-21">Value</option>
</select>

Any help is appreciated.
????: NamePros.com http://www.namepros.com/programming/362229-javascript-calculations.html

Thanks

Matthew. · 08-15-2007, 03:11 PM

Hi,

Can you elaborate a bit more please? You have the select there so I'm guessing you want to take the value of that and use it in a calculation but without more information I can't really provide much help.

As a tip, you can give the select an id and use it like this:

Code:

select = document.getElementById('selectid');
document.write(100 - select.value);

Encenta.com · 08-15-2007, 03:20 PM

Sorry, I was a bit rushed. Basically, I want to add the values of 5 dropdown boxes: dd[0], dd[1], dd[2], etc. and then display the calculated value in a div using innerHTML.

guillermobt · 08-16-2007, 12:41 PM

Code:

<script language="javascript">
//GLOBAL Var.
var maxIndex= 5; //Put the # of form fields (takes in mind it starts numbering with the 0)


///////////////////////////////////////
function Sumatory (f, numFields) {
///////////////////////////////////////
  var sumatory= 0;
  for (k=0; k < numFields; k++) {
    theValue= f.dd[k].value;
    if (!(isNaN(theValue))) {
      sumatory+= parseInt(theValue);
    }
  }
  //return (sumatory);
  document.getElementById('visor').innerHTML= sumatory;
}

</script>

Add a DIV with ID="visor" somewhere in your code:
????: NamePros.com http://www.namepros.com/showthread.php?t=362229

Code:

<div id="visor"></div>

Add a button in your form, something like this:

Code:

<input type="button" value="Add values"
  onClick="Sumatory (this.form, maxIndex)">

I personally would use Prototype library (www.prototypejs.org) to access DOM elements in a much powerful way. Once you use it, you'll love it.

Couldn't test the code, so I hope not to have made a syntax error or something like that.

Regards.

08-15-2007, 02:17 PM	THREAD STARTER #1 (permalink)
Encenta.com SQLdumpster.com Join Date: Jun 2005 Location: West Sussex, UK Posts: 573 Follow @MiseriaSK	Javascript calculations Hi, I'm looking for a way to calculate a set of dropdown lists. Eg: HTML Code: <select name="dd[0]"> <option value="+21">Value</option> <option value="-21">Value</option> </select> Any help is appreciated. ????: NamePros.com http://www.namepros.com/programming/362229-javascript-calculations.html Thanks __________________ Encenta - Amazon Associates CMS

08-15-2007, 03:11 PM	#2 (permalink)
Matthew. Senior Member Join Date: Dec 2006 Location: England Posts: 1,568	Hi, Can you elaborate a bit more please? You have the select there so I'm guessing you want to take the value of that and use it in a calculation but without more information I can't really provide much help. As a tip, you can give the select an id and use it like this: Code: select = document.getElementById('selectid'); document.write(100 - select.value); __________________ University Grade Calculator juegosjuegos Your Hotel in Austria Matratzen

08-15-2007, 03:20 PM	THREAD STARTER #3 (permalink)
Encenta.com SQLdumpster.com Join Date: Jun 2005 Location: West Sussex, UK Posts: 573 Follow @MiseriaSK	Sorry, I was a bit rushed. Basically, I want to add the values of 5 dropdown boxes: dd[0], dd[1], dd[2], etc. and then display the calculated value in a div using innerHTML. __________________ Encenta - Amazon Associates CMS

08-16-2007, 12:41 PM	#4 (permalink)
guillermobt NamePros Member Join Date: Sep 2005 Posts: 160	Code: <script language="javascript"> //GLOBAL Var. var maxIndex= 5; //Put the # of form fields (takes in mind it starts numbering with the 0) /////////////////////////////////////// function Sumatory (f, numFields) { /////////////////////////////////////// var sumatory= 0; for (k=0; k < numFields; k++) { theValue= f.dd[k].value; if (!(isNaN(theValue))) { sumatory+= parseInt(theValue); } } //return (sumatory); document.getElementById('visor').innerHTML= sumatory; } </script> Add a DIV with ID="visor" somewhere in your code: ????: NamePros.com http://www.namepros.com/showthread.php?t=362229 Code: <div id="visor"></div> Add a button in your form, something like this: Code: <input type="button" value="Add values" onClick="Sumatory (this.form, maxIndex)"> I personally would use Prototype library (www.prototypejs.org) to access DOM elements in a much powerful way. Once you use it, you'll love it. Couldn't test the code, so I hope not to have made a syntax error or something like that. Regards. Last edited by guillermobt; 08-16-2007 at 12:45 PM. Reason: add a parseInt!

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