Question

i have this code:

<script type="text/javascript">
var str="KD-R35H2UND";
var patt1=/[G|T|EE|EJU].*D/i;
document.write(str.match(patt1));
</script>

by using code at var patt1=... i can show like this:

if i type KD-R35ED => SHOW ED
KD-R35UND => UND
KD-R35JD => JD
KD-R35TJD => TJD
KD-R35EED=> EED

my problem is: if i type KD-R35GD it can show GD but if KD-R35D it can’t show anything..how to make it works?

Answer 1

b* means “match zero or more occurences of b“.

. means “match any character except newline”.

[EE|EJU] means “match an E, a |, a J or a U“.

.* means “match any character except newline zero or more times”.

D means “match a D“.

So the regex is doing what you asked it to do.

From the examples you provided in your question, I’m guessing that the actual rules should be:

1. String starts with KD-R35.
2. Then any number of alphanumeric characters may follow, as long as
3. there is an E, a J or a U among them, and
4. the string ends in D.

These rules, as a regex, read:

^         # start of string
KD-R35    # literal text
(         # start of capturing group
  \w*     # any number of alphanumeric characters
  [EJU]   # at least one of E, J, or U
  \w*     # any number of alphanumeric characters
  D       # a D
)         # end of capturing group
$         # end of string

or, in JavaScript:

match = subject.match(/^KD-R35(\w*[EJU]\w*D)$/i);
if (match != null) {  // successful match
    mytext = match[1] // capturing group 1
} else {
    // Match attempt failed
}

I’m assuming that upper/lowercase don’t matter.

EDIT: Erm, your new edit changes the rules. It seems that any string is allowed as long as it starts with KD-R35 and ends in D. In this case, the regex would simply be /^KD-R35(\w*D)$/i.