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ewaldron
12-16-2003, 10:08 AM
I am trying to validate a form field with Javascript.the 1st 2 letters in the field have to begin with chars eg."CS" and the next four digits have to be numerical values eg."4557"
any ideas??
Geat
12-16-2003, 10:49 AM
Use a regular expression of the form

var myregExp = /[A-Z][A-Z][0-9][0-9][0-9][0-9]/;

and use

result = myregExp.test(document.formname.inputname.value);

If this returns true, the input value is valid.
ewaldron
12-16-2003, 11:35 AM
Thanks, but i dont see how result is incorporated into the script.

is "var myregExp = /[A-Z][A-Z][0-9][0-9][0-9][0-9]/;" Javascript syntax or are you trying to explain to me 2 chars-then 4 numbers??

how do i link the result variable to the myRegExp variable??
Geat
12-17-2003, 02:45 AM
I'm not sure how familiar you are with the concept, but that bunch of characters is what's known as a regular expression - it's a way of matching patterns within a string.

[0-9] means that the character must be a digit from 0 to 9, and [A-Z] means it must be a capital letter (if you want to use any letter, you can use [A-Z][a-z]).

The full code you'd need is something like this:


<SCRIPT>
function checkForm() {
var myregExp = /[A-Z][A-Z][0-9][0-9][0-9][0-9]/;
if (!myregExp.test(myform.usercode.value)) {
alert("Please enter a valid code");
return false;
} else {
return true;
}
}
</SCRIPT>

<HTML>
<FORM NAME="myform" ONSUBMIT="return checkForm();">
<INPUT type="text" name="usercode">
<INPUT type="submit">
</FORM>
</HTML>
Jeff Mott
12-17-2003, 03:35 AM
[A-Z][a-z]Note that this will not match any letter, it will match a capital letter followed by a lowercase letter.

The expression can also be simplified with predefined character classes and quantifiers./^[a-z]{2}\d{4}$/i
Geat
12-17-2003, 03:39 AM
Touché, I meant [A-Za-z], but yeah - your purified way is better, if a little harder to read for newbies to the world of regular expressions.