Entry

how can I do a javascript edit check for floating point number on a form.

Apr 4th, 2008 19:47
ha mo, Iván Rivera, Robin Jaggassar,

You only have to remember that JavaScript sees all values of form
elements as text strings. The easiest way to check if a certain string
is a floating point number is applying to it the parseFloat() global
function, which returns the floating point number that corresponds to a
given string (parseFloat('42.4242') returns 42.4242 as a number), or NaN
(not a number) if the string given is not a valid representation for a
floating point number.
The global function isNaN() helps also, determining if a given number is
NaN or some other thing (a real number, infinite or minus infinite). So
your validation code could look like this:
  myString=myForm.myInputText.value;
  if (isNaN(parseFloat(myString))) alert('Not a number');
There is also a isInfinite() global function to help with the infinite
case, working the same way than isNaN().
I hope this was useful...
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