jQuery Data vs Attr: Understanding the Differences

In jQuery, both $.data and $.attr are used to manipulate attributes in DOM elements. However, they serve distinct purposes and differ in their usage and behavior.

When to Use $.data

$.data is primarily used to store data associated with a DOM element within jQuery's internal cache ($.cache). This data is not stored as HTML attributes on the element itself. Hence, if you need to store data persistently for data-binding or custom scripting purposes, $.data is the preferred choice.

Example:

$('#foo').data('myData', 'someValue');
// Gets the stored data
$('#foo').data('myData'); // outputs "someValue"

When to Use $.attr

$.attr, on the other hand, primarily sets or retrieves HTML5 data-attributes. These data-attributes are stored as attributes on the DOM element and are intended to provide additional metadata or content.

Example:

$('#foo').attr('data-attribute'); // outputs "myCoolValue"
$('#foo').attr('data-attribute', 'newValue'); // Sets the data-attribute to "newValue"

Additional Considerations

• Data storage with $.data supports complex objects, whereas HTML data-attributes can only contain strings.
• $.data auto-casts values into their appropriate types when retrieving data, such as converting "true" to a boolean.
• $.attr preserves the original data type when retrieving data.
• To avoid confusion, it is recommended to use camelCase syntax when accessing data stored with $.data.
• You can also use $.removeAttr to remove data-attributes, which does not have a direct equivalent with $.data.