Programming Forums > Web Development and Design > JavaScript and Client-Side Browser Scripting

Navid · Mar 25th, 2005, 12:09 PM

x = 4.2

If (x "has a decimal")

how do i get JS to check if it has a decimal?

Navid · Mar 26th, 2005, 10:26 PM

nevermind, i figured a solution

tempest · Mar 27th, 2005, 6:33 PM

if(parseInt(x) != x)

mackenga · Apr 1st, 2005, 9:52 AM

Another method would be to check:

(Toggle Plain Text)

// return nonzero if x has a fractional part; nonzero otherwise
function hasDecimalPoint(x) {
  return (x.toString().indexOf(".") + 1);
}

(Haven't tested that but I think it should work; if not, the general idea is that if there's no decimal point, indexOf(".") in the string version (x.toString()) should be -1.)

Actually, assuming it does work, it will have a slightly weird behaviour if passed something that isn't a number at all... but used as it expects to be, it should be a decent solution.

Infinite Recursion · Apr 1st, 2005, 10:30 AM

(Toggle Plain Text)

function isDecimal(field)
{

var validTxt = /^[0-9.]+$/
var msg = "Not a valid decimal.";
if (! validTxt.test(field.value))
{
alert(msg);
return false;
}
else
{
return true;
}
}

mackenga · Apr 2nd, 2005, 4:33 PM

Oooh, I must confess I've never seen a regexp used in JavaScript. Is that a feature of the language or does it use some sort of library?

Mar 25th, 2005, 12:09 PM	#1
Navid Hobbyist Programmer Join Date: Feb 2005 Location: Canada Posts: 187 Rep Power: 4	If it has a decimal x = 4.2 If (x "has a decimal") how do i get JS to check if it has a decimal?

Apr 1st, 2005, 9:52 AM	#4
mackenga Professional Programmer Join Date: Mar 2005 Location: Glasgow, Scotland Posts: 321 Rep Power: 4	Another method would be to check: (Toggle Plain Text) // return nonzero if x has a fractional part; nonzero otherwise function hasDecimalPoint(x) { return (x.toString().indexOf(".") + 1); } // return nonzero if x has a fractional part; nonzero otherwise function hasDecimalPoint(x) { return (x.toString().indexOf(".") + 1); } (Haven't tested that but I think it should work; if not, the general idea is that if there's no decimal point, indexOf(".") in the string version (x.toString()) should be -1.) Actually, assuming it does work, it will have a slightly weird behaviour if passed something that isn't a number at all... but used as it expects to be, it should be a decent solution. Last edited by mackenga; Apr 1st, 2005 at 9:56 AM. Reason: Edited code example to make it a function

Apr 1st, 2005, 10:30 AM	#5
Infinite Recursion Programming Guru Join Date: Jul 2004 Location: United States Posts: 3,467 Rep Power: 8	(Toggle Plain Text) function isDecimal(field) { var validTxt = /^[0-9.]+$/ var msg = "Not a valid decimal."; if (! validTxt.test(field.value)) { alert(msg); return false; } else { return true; } } function isDecimal(field) { var validTxt = /^[0-9.]+$/ var msg = "Not a valid decimal."; if (! validTxt.test(field.value)) { alert(msg); return false; } else { return true; } } __________________ http://jasonpowers.net "There are a thousand hacking at the branches of evil to one who is striking at the root."

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Mar 26th, 2005, 10:26 PM	#2
Navid Hobbyist Programmer Join Date: Feb 2005 Location: Canada Posts: 187 Rep Power: 4	nevermind, i figured a solution

Mar 27th, 2005, 6:33 PM	#3
tempest Programming Guru Join Date: Oct 2004 Posts: 1,041 Rep Power: 6	if(parseInt(x) != x)

Apr 2nd, 2005, 4:33 PM	#6
mackenga Professional Programmer Join Date: Mar 2005 Location: Glasgow, Scotland Posts: 321 Rep Power: 4	Oooh, I must confess I've never seen a regexp used in JavaScript. Is that a feature of the language or does it use some sort of library?

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Programming Forums > Web Development and Design > JavaScript and Client-Side Browser Scripting

If it has a decimal