Equivalent of Format$ in Javascript?

**filburt1** · Nov 1st, 2001, 03:00 PM

I need a number to be in the form "######.##" (or at least two decimal places). Right now I'm using a convoluted system of ifs to do it, isn't there a better way?

scoutt · Nov 1st, 2001, 03:09 PM

here is a rounding 2 to decimal places. not sure if it will help, but might give you some ideas.

EX: 7.9 equals 7.90, or 7.777 equals 7.78, and so on.

Code:

<html> 
<head> 
<title>Untitled</title> 
<script language=javascript> 
Function roundIt(amount) 
{ 
var s = ""; 
var Decimal; 
amount = parseFloat(amount); 
If (!(isNaN(amount))) { 
// round to nearest cent 
amount = Math.round(amount * 100); 
amount = amount / 100; 

// format the output 
s = New String(amount); 
Decimal = s.indexOf("."); 
If (Decimal == -1) { 
// whole number 
s+= ".00"; 
} Else { 
If (Decimal == (s.length - 2)) { 
// needs a trailing zero 
s+= "0"; 
} 
} 
} Else { 
// not a number so return zero 
s = "0.00"; 
} 
document.form1.Text1.value=s; 
//calculate(); 
Return s; 
} 
</script> 
</head> 
<body> 
<form Name=form1> 
<br><br> 
<Input Type=Text Name=Text1 onBlur="roundIt(this.value)"> <Input Type=button value="Round It" onClick="roundIt(document.form1.text1.value)"> 
<br> 
</body> 
</html>

**filburt1** · Nov 1st, 2001, 03:10 PM

Yeah, that's what I was doing (I am having it only go to one place because of how complex it starts to get). I was hoping that something like Math.round() could help.

**filburt1** · Nov 1st, 2001, 03:14 PM

So much for Math.round: http://home.netscape.com/eng/mozilla...ef_r-r.htm#308

BTW, I forgot the most important thing: if it rounds to something like 1.10, 1.00, 3.20, 4.00, etc., I need the trailing zeros.

**filburt1** · Nov 2nd, 2001, 12:15 PM

*ahem*

chenko · Nov 2nd, 2001, 03:28 PM

Originally posted by filburt1
So much for Math.round: http://home.netscape.com/eng/mozilla...ef_r-r.htm#308

BTW, I forgot the most important thing: if it rounds to something like 1.10, 1.00, 3.20, 4.00, etc., I need the trailing zeros.

dont you mean leading zeros

**filburt1** · Nov 2nd, 2001, 04:18 PM

0001 = leading, 1.000 = trailing

chenko · Nov 5th, 2001, 04:11 AM

Originally posted by filburt1
BTW, I forgot the most important thing: if it rounds to something like 1.10, 1.00, 3.20, 4.00, etc., I need the trailing zeros.

"######.##"

ummm, 1.10 and , 1.00 already have the trailing zeros, and you are saying that you need trailing? ummm, i would rather need leading zeros to get ######.##

scoutt · Nov 6th, 2001, 10:26 PM

here try this...

Code:

function formatNumber(expr, decimals) {
         var str = "" + Math.round( eval(expr) * Math.pow(10,decimals))
         while (str.length <= decimals) { str = "0" + str } // maybe add some leading zeros
         var decpoint = str.length - decimals // find location of decimal point
         var result = str.substring(0,decpoint);
         if (decimals) result += "." + str.substring(decpoint,str.length);
         return result;
}

eg. formatNumber(7.777,2) returns "7.78"
formatNumber(1+1,2) returns "2.00"
formatNumber(20/3,0) returns "7"
At the moment it evaluates an expression as input, but doesn't check for rubbish input, but you could change that by doing:
function formatNumber(num, decimals) {
if (isNaN(parseFloat(num)) return "0";
var str = "" + Math.round( parseFloat(num) * Math.pow(10,decimals))
etc.

**filburt1** · Nov 7th, 2001, 05:51 PM

Thanks, I'll try it out.

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