Need help with regular expression and form field check

[Tommy]

I am a complete beginner in regular expressions and would need some help
from the group regarding checking a form field.

I have a field on the form where users enters a text string. The user should
only be able to enter a string in the format of firstname.lastname or
firstname.initial.lastname. Firstname/initial/lastname can be any characters
between a-z and there should be a dot between those. How should the
javascript look like to check this?

br,

Tommy

[Michael Winter]

On Tue, 21 Sep 2004 18:18:18 +0300, Tommy
<to*********@REMOVETHISrasku.net> wrote:

[snip]

I have a field on the form where users enters a text string. The user
should only be able to enter a string in the format of
firstname.lastname or firstname.initial.lastname.
Firstname/initial/lastname can be any characters between a-z and there
should be a dot between those. How should the javascript look like to
check this?

If you want to check the format, nothing more, then use:

/^[a-z]+\.[a-z]+(\.[a-z]+)?$/i.test(value)

which will return true for a match, false otherwise.

If you want to extract the values, use:

var r = /^([a-z]+)\.([a-z]+)(\.([a-z]+))?$/i.exec(value);

if(r) {
var first, init, last;

first = r[1];
if(3 == r.length) {
last = r[2];
} else {
init = r[2];
last = r[4];
}
}

By the way, I don't think it's a good idea to get the user to enter their
full name delimited by periods; it's not particularly natural. Two text
boxes with an optional third would be better.

Hope that helps,
Mike

--
Michael Winter
Replace ".invalid" with ".uk" to reply by e-mail.

[Lee]

Tommy said:

I am a complete beginner in regular expressions and would need some help
from the group regarding checking a form field.

I have a field on the form where users enters a text string. The user should
only be able to enter a string in the format of firstname.lastname or
firstname.initial.lastname. Firstname/initial/lastname can be any characters
between a-z and there should be a dot between those. How should the
javascript look like to check this?

You haven't specified a minimum or maximum length for firstname
or lastname, so "frank.b", "f.baker" and "f.r.b" are all valid.
That might be best, since there may be a few people with single
character names. This does mean that you can't detect when the
user has entered "initial.lastname" or "firstname.initial".

"Frank.R.Baker" is not valid, because you specified a-z. If that
was an oversight, add an "i" after the ending "/" of the RegExp.

function validate(str){
if(-1==str.search(/^[a-z]+(\.[a-z]){0,1}(\.[a-z]+){0,1}$/)){
alert("\""+str+"\"\nis not in the correct format.");
}else{
alert("ok");
}
}

[Michael Winter]

After reading Lee's post, I see I made a mistake. Corrections are below.

On Tue, 21 Sep 2004 16:00:00 GMT, Michael Winter
<M.******@blueyonder.co.invalid> wrote:

[snip]

If you want to check the format, nothing more, then use:

/^[a-z]+\.[a-z]+(\.[a-z]+)?$/i.test(value)
/^[a-z]+(\.[a-z])?\.[a-z]+$/i.test(value)

[snip]
If you want to extract the values, use:

var r = /^([a-z]+)\.([a-z]+)(\.([a-z]+))?$/i.exec(value);

if(r) {
var first, init, last;

first = r[1];
if(3 == r.length) {
last = r[2];
} else {
init = r[2];
last = r[4];
}
}

var r = /^([a-z]+)(\.([a-z]))?\.([a-z]+)$/i.exec(value);

if(r) {
var first, init, last;

first = r[1];
init = r[3];
last = r[4];
}

where init will be an empty string if no inital was entered.

[snip]

Mike

--
Michael Winter
Replace ".invalid" with ".uk" to reply by e-mail.

[Ivo]

"Lee" wrote

Tommy said:

I am a complete beginner in regular expressions and would need some help
from the group regarding checking a form field.

I have a field on the form where users enters a text string. The user shouldonly be able to enter a string in the format of firstname.lastname or
firstname.initial.lastname. Firstname/initial/lastname can be any charactersbetween a-z and there should be a dot between those. How should the
javascript look like to check this?

Don't forget the infamous O'Briens of this world. Apostrophes, spaces and
some other weird characters are all very possible in a name.
--Iv