regex against spaces

Question

I'm not a regex guy, so I definitely need help on this.

All I want is to have a regular expression to validate if the user inputted on "username" will contain no spaces.

Currently, I have this structure:

if($('.username').val().length < 5) {
  $(".user_account_validation").html("Too shorty.").css('background-color', 'red');
} else if() {
}

As you can notice my else if() is still empty, and in that I want to place my validation. If the username has space I'll return a corresponding error message. Thanks!

ironchefpython · Accepted Answer · 2012-02-13 02:45:21Z

6

Some people, when confronted with a problem, think "I know, I'll use regular expressions." Now they have two problems. --Jamie Zawinski

If all you want to know is if there are spaces in the input, the following will return -1 if there are no spaces in the input, and the index of the first space otherwise.

$('.username').val().indexOf(' ');

If you need a regular expression the following will return the index of the first whitespace, and -1 otherwise.

$('.username').val().search(/\s/);

answered Feb 13, 2012 at 2:45

ironchefpython

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2 Comments

Niklas B. Over a year ago

This question is a perfect counter-example of Jamie's rule. This is because the language to match here actually IS regular.

ironchefpython Over a year ago

@NiklasB. I will stipulate that it is a decent place to use a Regex, and in fact if the OP asked "how do I check for valid input", I would have pointed him to a Regex, but the quote is a knee-jerk response to, "I have problem X, how do use a Regex for it?". Ideally, we should all look at every tool in our toolbox, rather than seeing everything as a nail to be pounded with a Regex hammer.

ThiefMaster · Accepted Answer · 2012-02-13 11:26:19Z

4

No need to use a regex. You can simply use $('.username').val().indexOf(' ') !== -1 to test if it contains any spaces.

Note that it does not prevent the user from entering tabs via copy&paste, but you need validation on the server side anyway, so if you check for things regular users won't enter over there, it's sufficient.

edited Feb 13, 2012 at 11:26

answered Feb 13, 2012 at 2:45

ThiefMaster

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3 Comments

user1106925 Over a year ago

What about tabs, newlines, etc...?

Niklas B. Over a year ago

Actually a regex would be really fitting here, why not suggest it (especially because it was asked for)?

ThiefMaster Over a year ago

Unless you use copy&paste or have a textarea you cannot enter tabs/newlines anyway. But you are right, if you want to block all whitespace a regex is better.

zellio · Accepted Answer · 2012-02-13 02:48:10Z

3

you could use indexOf for just ' '

else if ( $('.username').val().indexOf(' ') === -1 ) {
    //do stuff
}

but if you need to match anywhite space then use this

else if ( $('.uername').val().match(/\s/) {
    //do stuff
}

answered Feb 13, 2012 at 2:48

zellio

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