Need assistance dealing with "0" value in calculation

[bigblock454]

Hi All, I need help dealing with a "0" value and division. I have 4 fields in a form that take a value from another field and either divide that value by 4, or return a "0" value. I tried to trick it by assigning a variable as "1", but this is not working correctly and I am not a JS programmer, more of an at-need wannabe. So...Here is the script (var b is one of each of 4 fields, so that changes), any assistance would be invaluable!

var a = this.getField("TotalCommission2");
var b = this.getField("Up1");
//or Demo1, Contract1, etc
if ((b.value == 0)) {
event.value = 0
} else {
var d = (a.value/4)
var c = 1
event.value = d*c
}

 

[kaht]

The problem is that "0" is not the same as 0. When you pull info out of a text field it is automatically treated as a string. If you want to make numeric comparisons to that string, you must first convert it to an integer or float (if it has a decimal). The javascript functions to do this are parseInt and parseFloat, respectively.

Try making this change to your code:

var a = this.getField("TotalCommission2");
var b = this.getField("Up1");
//or Demo1, Contract1, etc
if (([!]parseInt([/!]b.value[!], 10)[/!] == 0)) {
event.value = 0
} else {
var d = ([!]parseInt([/!]a.value[!], 10)[/!]/4)
var c = 1
event.value = d*c
}

-kaht

Lisa, if you don't like your job you don't strike. You just go in every day and do it really half-assed. That's the American way. - Homer Simpson

[small]<P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <.</B>[/small]

 

[bigblock454]

kaht, thanks! One thing, you mentioned a decimal, these values definitely have a decimalm as they are dollars. Would this be better? (hat tip to MikeyJudd for showing me the syntax on another thread):

var a = parseFloat(this.getField("TotalCommission2").value);
var b = parseFloat(this.getField("Up1").value);
//or Demo1, Contract1, etc
if ((parseInt(b.value, 10) == 0)) {
event.value = 0
} else {
var d = (parseInt(a.value, 10)/4)
var c = 1
event.value = d*c
}

 

[Ascalonian]

A question that pops into my head is if the value is entered by a user?

If so, I would account for human error and do a check to make sure the value is a number.

var a = this.getField("TotalCommission2");
var b = this.getField("Up1");
//or Demo1, Contract1, etc

var aInt = parseInt(a.value, 10);
var bInt = parseInt(b.value, 10);

if (!isNaN(aInt) && !isNaN(bInt)) {
    if (bInt == 0)) {
        event.value = 0
    } else {
        var d = (parseInt(a.value, 10)/4);
        var c = 1;
        event.value = d*c;
    } 
}else {
    alert('Value entered is not a valid number');
}

 

[kaht]

bigblock454, a slight change to your code:

var a = parseFloat(this.getField("TotalCommission2").value);
var b = parseFloat(this.getField("Up1").value);
//or Demo1, Contract1, etc
if (([s]parseInt([/s][!]b[/!][s].value, 10)[/s] == 0)) {
event.value = 0
} else {
var d = ([s]parseInt([/s][!]a[/!][s].value, 10)[/s]/4)
var c = 1
event.value = d*c
}

If you parse the values as they are assigned as floats, make sure that you don't convert them to integers later down in the page - that would eliminate the whole point of converting them to floats in the first place.

MikeyJudd also brings up a good point - it is a good idea to check for NaN (not a number) to ensure that your code doesn't crash as a result of non-numeric values being entered.

-kaht

Lisa, if you don't like your job you don't strike. You just go in every day and do it really half-assed. That's the American way. - Homer Simpson

[small]<P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <.</B>[/small]

 

[bigblock454]

Ok, I am a little lost on the integer vs float values. All values on this form are dollars with the exception of the var b values, which are normally either a "0" indicating that there is no payment due for that 25% of the overall commission due, or a "1" indicating that the value is 25% of the commission due. It POTENTIALLY could be a value of .5, or .25 as well, but that would be a rarity. I agree that user error is always a factor, so the a;ert is a good thing!

 

[kaht]

Ok, I am a little lost on the integer vs float values.

Integer values:

1, 69, 78199101, 0, -69

Float Values:
1, -123, 5.681, 69.69, -.00001

Basically, if it has a decimal it needs to be defined as a float, if it doesn't need a decimal, then it *can* be defined as an integer - but could also be a float.



-kaht

Lisa, if you don't like your job you don't strike. You just go in every day and do it really half-assed. That's the American way. - Homer Simpson

[small]<P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <.</B>[/small]

 

[bigblock454]

OK, thanks. Now, can you explain what the 10 is for on the lines:


if ((parseInt(b.value, 10) == 0)) {
event.value = 0
} else {
var d = (parseInt(a.value, 10)/4)

and would I modify them to be:

if ((parseFloat(b.value, 10) == 0)) {
event.value = 0
} else {
var d = (parseFloat(a.value, 10)/4)

 

[bigblock454]

Hi again, I tried the following code and get a syntax error for the 10th line "event.value = 0" :

var a = this.getField("TotalCommission2");
var b = this.getField("Up1");
//or Demo1, Contract1, etc

var aInt = parseInt(a.value, 10);
var bInt = parseInt(b.value, 10);

if (!isNaN(aInt) && !isNaN(bInt)) {
if (bInt == 0)) {
event.value = 0
} else {
var d = (parseInt(a.value, 10)/4);
var c = 1;
event.value = d*c;
}
}else {
alert('Value entered is not a valid number');
}

 

[Ascalonian]

Put double quotes around the 0

 

[bigblock454]

Mikey, if I do it like this it still gives me a syntax error (I also tried it as "0"; & 0; still get the error):

var a = this.getField("TotalCommission2");
var b = this.getField("Up1");
//or Demo1, Contract1, etc

var aInt = parseInt(a.value, 10);
var bInt = parseInt(b.value, 10);

if (!isNaN(aInt) && !isNaN(bInt)) {
if (bInt == 0)) {
event.value = "0"
} else {
var d = (parseInt(a.value, 10)/4);
var c = 1;
event.value = d*c;
}
}else {
alert('Value entered is not a valid number');
}

 

[kaht]

can you explain what the 10 is for on the lines

http://www.w3schools.com/jsref/jsref_parseInt.asp

It's the radix value for number. Essentially it determines if the number is binary, octal, decimal, hexadecimal, etc. Providing a value of 10 explicitly states that you're parsing a base-10 (decimal) number. 99 times out of 100 the 10 isn't needed, but if you read the link I posted you'll see "If the string begins with "0", the radix is 8 (octal)." This means that if a user types in a number like "0123456" and you parseInt it w/o specifying base-10, you're going to get very unexpected results. Try it for yourself:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "[URL unfurl="true"]http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">[/URL]
<html xmlns="[URL unfurl="true"]http://www.w3.org/1999/xhtml">[/URL]
<head>
<title>test</title>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" />
<script type="text/javascript">

window.onload = function () {
   var a = "01234";
   alert(parseInt(a));
   alert(parseInt(a, 10));
};

</script>
<style type="text/css"></style>
</head>
<body>
</body>
</html>

-kaht

Lisa, if you don't like your job you don't strike. You just go in every day and do it really half-assed. That's the American way. - Homer Simpson

[small]<P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <.</B>[/small]

 

[Ascalonian]

Can you paste the syntax error into here?

Also, don't forget the semi-colon.

event.value = '0';

 

[bigblock454]

kaht, ok, I just stuck in an editor and it first returned a 668, and then a 1234. My script is for a fillable PDF though, not a webpage I'll read the link!

 

[Lowet]

hi!

I've looked at your code some times now and have some questions.

¤ What is the event.value?
Javascript should through an error here because "event" is a predifined object for events and it doesn't have a property "value". So you should change the "event" to something else..

¤ What is the this.getField()?
Is "getField" a function you wrote? And how is the script triggered? Because the "this" can only be accessed like:

On the element:
<input onchange="alert(this.value);">

In a object:
var obj = {
          a_value:'hello',
          aMethod:function ()
                  {
                  alert(this.a_value);
                  }
          };

but not in functions..
well, it they are not triggered with new:
var a = new aFunction();

And always use the parseFloat when dealing with money.

 

[Lowet]

Here is how I would write it if I understood what you want the function to do..

var a,b,ev;
a = parseFloat(document.forms[0]['TotalCommission2'].value);
b = parseFloat(document.forms[0]['Up1'].value);

if (b == 0) {ev = 0;}
else {ev = a/4;}

It's hard to help when I don't really know what the code is intended to do..

 

[kaht]

lowet, why not condense it a little more:

var a = parseFloat(document.forms[0]['TotalCommission2'].value);
var b = parseFloat(document.forms[0]['Up1'].value);
var ev = ((b) ? a : 0) / 4;

This, of course, takes out any kind of data integrity check and assumes that the values entered are numeric.

-kaht

Lisa, if you don't like your job you don't strike. You just go in every day and do it really half-assed. That's the American way. - Homer Simpson

[small]<P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <B> <P> <.</B>[/small]

 

[Ascalonian]

I still think you should check the value with isNaN due to users typing this in manually. Humans make mistakes... I call this ID-10-T errors. )

 

[Lowet]

Yes, kaht, that's also a possibility. I just wanted him to easyly read the code. I use to use the ?: statements very often instead of the if/else in my scripts..

- Lowet

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