Simple Javascript validation for numbers only?

[kapow]

I have a simple (non expert) form validation javascript, e.g. part of it:

if (MyForm.SoAndSo.value.length<5)
{ message += "- Item SoAndSo... not enough characters";
submitOK="False"; }

Can anyone tell me the javascript code I should use to check for numbers only in a variable (ie no alphabetics or special characters).

[ytswy]

The function isNaN() returns True if the argument is NOT a number - NaN = Not a Number

I've a feeling a read somewhere that it returns true for negative numbers rather than false but I'm not sure of that.

[kapow]

Thanks Ytswy

Can you tell me how I should use isNaN() in my javascript (I am not very good at javascript). E.g. would it be something like:

if (MyForm.QuantityReq.value isNaN())
{ message += "- Please enter your quantity as a number.";
submitOK="False"; }

[ytswy]

My javascript syntax is a little weak also, but I think it would be something like this:

if (isNaN(MyForm.QuantityReq.value))
{ message += "- Please enter your quantity as a number.";
submitOK="False"; }

[kapow]

THANKYOU Ytswy
IT WORKS FINE :)