[javascript] The data-toggle attributes in Twitter Bootstrap

For example, say you were creating a web application to list and display recipes. You might want your customers to be able to sort the list, display features of the recipes, and so on before they choose the recipe to open. In order to do this, you need to associate things like cooking time, primary ingredient, meal position, and so on right inside the list elements for the recipes.

<li><a href="recipe1.html">Borscht</a></li>
<li><a href="recipe2.html">Chocolate Mousse</a></li>
<li><a href="recipe3.html">Almond Radiccio Salad</a></li>
<li><a href="recipe4.html">Deviled Eggs</a></li>

In order to get that information into the page, you could do many different things. You could add comments to each LI element, you could add rel attributes to the list items, you could place all the recipes in separate folders based on time, meal, and ingredient (i.e. ). The solution that most developers took was to use class attributes to store information about the current element. This has several advantages:

• You can store multiple classes on an element
• The class names can be human readable
• It’s easy to access classes with JavaScript (className)
• The class is associated with the element it’s on

But there are some major drawbacks to this method:

• You have to remember what the classes do. If you forget or a new developer takes over the project, the classes might be removed or changed without realizing that that affects how the application runs.
• Classes are also used for styling with CSS, and you might duplicate CSS classes with data classes by mistake, ending up with strange styles on your live pages.
• It’s more difficult to add on multiple data elements. If you have multiple data elements, you need to access them in some way with your JavaScript, either by the name of the class or the position in the class list. But it’s easy to mess up.

All the other methods I suggested had these problems as well as others. But since it was the only way to quickly and easily include data, that’s what we did. HTML5 Data Attributes to the Rescue

HTML5 added a new type of attribute to any element—the custom data element (data-*). These are custom (denoted by the *) attributes that you can add to your HTML elements to define any type of data you want. They consist of two parts:

Attribute Name This is the name of the attribute. It must be at least one lowercase character and have the prefix data-. For example: data-main-ingredient, data-cooking-time, data-meal. This is the name of your data.

Attribute Vaule Like any other HTML attribute, you include the data itself in quotes separated by an equal sign. This data can be any string that is valid on a web page. For example: data-main-ingredient="chocolate".

You can then apply these data attributes to any HTML element you want. For example, you could define the information in the example list above:

<li data-main-ingredient="beets" data-cooking-time="1 hour" data-meal="dinner"><a href="recipe1.html">Borscht</a></li>
<li data-main-ingredient="chocolate" data-cooking-time="30 minutes" data-meal="dessert"><a href="recipe2.html">Chocolate Mousse</a></li>
<li data-main-ingredient="radiccio" data-cooking-time="20 minutes" data-meal="dinner"><a href="recipe1.html">Almond Radiccio Salad</a></li>
<li data-main-ingredient="eggs" data-cooking-time="15 minutes" data-meal="appetizer"><a href="recipe1.html">Deviled Eggs</a></li>

Once you have that information in your HTML, you will be able to access it with JavaScript and manipulate the page based on that data.