Posts Tagged ‘data attributes’

I recently worked on a project that involved creating promotion codes for our clients. I wanted to make this tool as simple as possible to use and because this involved dealing with thousands of our products in dozens of categories with custom pricing for each of these products, I had to find a generic way to deal with client-side form validation. I didn’t want to write custom JavaScript functions for each of the required inputs, so I decided to use custom data attributes.

Last month, we started a series focusing on web development tips and tricks with a post about JavaScript optimization. In this installment, we’re cover how to use HTML5 custom data attributes to assist you in validating forms.

Custom data attributes for elements are “[attributes] in no namespace whose name starts with the string ‘data-’, has at least one character after the hyphen, is XML-compatible, and contains no characters in the range U+0041 to U+005A (LATIN CAPITAL LETTER A to LATIN CAPITAL LETTER Z).” Thanks W3C. That definition is bookish, so let’s break it down and look at some examples.

Valid:

<div data-name="Philip">Mr. Thompson is an okay guy.</div>
<a href="softlayer.com" data-company-name="SoftLayer" data-company-state="TX">SoftLayer</a>
<li data-color="blue">Smurfs</li>

Invalid:

// This attribute is not prefixed with 'data-'
    <h2 database-id="244">Food</h2>
 
// These 2 attributes contain capital letters in the attribute names
    <p data-firstName="Ashley" data-lastName="Thompson">...</p>
 
// This attribute does not have any valid characters following 'data-'
    <img src="/images/pizza.png" data-="Sausage" />

Now that you know what custom data attributes are, why would we use them? Custom attributes allow us to relate specific information to particular elements. This information is hidden to the end user, so we don’t have to worry about the data cluttering screen space and we don’t have to create separate hidden elements whose purpose is to hold custom data (which is just bad practice). This data can be used by a JavaScript programmer to many different ends. Among the most common use cases are to manipulate elements, provide custom styles (using CSS) and perform form validation. In this post, we’ll focus on form validation.

Click through for a detailed, step-by-step example. »