Newbie really REALLY needs help ASAP

Hi all, I'm a newbie to javascript programming and am really stuck on something so silly.
I'm trying to create a function that will check a string of four characters and will only
return TRUE if all the characters are numeric.

I have made the function 'isNumeric' (shown below) and the function 'checkString' (also
shown below). Problem is, my 'checkString' function is wrong because everytime I run
it (as it is at the moment), I get TRUE if only the first character is numeric. The function
seems to ignore the other characters. Please can someone help.


function isNumeric(character)
/*
* Function returns true if its single-character string
* argument is a digit (0 to 9).
* Required for implementation of input checking function.
*/

{
return (character>='0')&&(character<='9')
}


function checkString(aString)

/*
* aString is a string. Function returns
* true if aString consists of a sequence
* of fours digits, false otherwise.
*/

{

if (aString.length != 4)
{
return false
};
for (var index = 0; index < 4; index = index + 1)
{
if (!isNumeric(aString.charAt(index)))
{
return false
}
else
{
return true
}
}
}

Thanks anyone who is nice enough to help me.

The Tone

If you are checking for digits, then remove the quotes around the 0 and 9 in the isNumeric function - quotes signify an string, not a number.

It's bailing after your first character because you're returning whether isNumeric returns true or false. So the function's always going to exit after the first loop iteration. Within the loop, return false only if isNumeric returns false. Then return true after the loop so you get a valid return if the condition inside the loop, but remove the else that returns true as the default behavior for each iteration.