HTML5 Form Validation Now!

Posted on Jan 9, 2011
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OK, originally this post should have been about h5Validate, a very simple and lightweight plugin for jQuery that handles two specific parts of the whole forms/webforms 2.0 part of HTML5: input patterns and the required-attribute. But then I stumbled upon the new form validation module of jQuery tools, one of those plugins I’m close to add by default to every project I’m working on. Oh boy …

h5Validate

But first things first: h5Validate right now handles two major form additions in HTML5: Allowing to mark fields as required and offers client-side validation for input fields that have a pattern attached to them. This is right now just a small subset of what browsers will hopefully eventually support natively when it comes to form validation but the plugin looks like a nice start. As with all the plugins I’m going to mention here, h5Validate does not only try to stick to the standard but go beyond it in some areas.

As an example: right now h5Validate only validates fields on focus-related events (e.g. blur) while for instance Firefox 4 does the validation when the user tries to submit the form. You can also create a central place for patterns and then apply them to multiple elements:

<script type="text/javascript">
    $(function() {
        $.h5Validate.addPatterns({
            phone: /[0-9]{13}/
        });
        $('form').h5Validate();
    });
</script>
<form method="post">
<input type="text" class="h5-phone" />
</form>

The current version is 0.3.x so there is probably still quite a lot in the future for this plugin, but especially when it gets submit-support and custom error messages (which are both on the TODO list right now) it will really become interesting :-) For now it seems like the field’s title attribute is the only way to customize the error message (similar to what FF4 has by default). And you have to provide your own element to display the error message in, compared to a custom widget handling that for you in the next Firefox version.

Right now there are quite a few HTML5 form related plugins out there that all only implement a subset of what HTML5 has to offer with regards to forms and their validation. Besides h5Validate there is for instance html5form which handles placeholders, required fields, autocomplete=off as well as some non-pattern related input validation. I’ve also found webforms2 which provides support for a rather impressive subset compared to the other two but doesn’t handle placeholders among other things and seems no longer maintained.

jQuery Tools Validator

Probably the biggest and most feature complete plugin for webforms 2.0 validation is the Validator module in jQuery tools. When I first saw it it was like X-Mas all over again. According to the docs it not only supports patterns, custom validators and required fields but also handles type=email, type=url and type=number out of the box. range and date input fields are support by two other modules.

For rendering the error messages it does not require that you change the markup but instead renders the required elements on its own. Thankfully it also doesn’t simply use the title attribute when rendering the error message but goes for a custom attribute (data-message) and falls back to globally defined ones. So while in other frameworks you would define the error message like this:

<input type="text" name="alphanum" pattern="[a-zA-Z0-9]" title="This field
    may only contain alpha-numeric characters" />

jQuery tools Validator keeps the title as an info-attribute and takes the error message from data-message like this:

<input type="text" name="alphanum" pattern="[a-zA-Z0-9]" title="Enter
    something here" data-message="This field
    may only contain alpha-numeric characters" />

And if your app already uses data-message for something else, you’re free to use a different attribute:

$('form').validator({
    'messageAttr': 'date-errormessage'
});

But these are just the not-localized error messages. The module offers a whole range of ways to also handle localized error messages.

As with practically any part of jQuery tools also the form validator offers a handful of custom events, in this case there are events for the whole form and also for specific fields. Just a small example: Let’s say you have a registration form and a new users comes by and wants to create a new account. Sadly her username is already taken and you want to offer her a few randomly generated options based on some parts of her registration details.

$('.registration-username').oninvalid(function(e, message) {
    // Fetch a list of names and render them.
    // ...
});

The only downside I could find so far about this is that the Validator module seems to have some issues with Firefox 4. But, given that FF4 is still in beta I guess it’s safe to assume that these issues will be fixed around the time 4.0 ships.

So, especially if you combine Validator with the Dateinput module it looks like a truly awesome package that I’m really looking forward to use in some future project :D OK, now I have to calm down, get a hot milk with honey or something …

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