Data attributes customize how a document displays content.
Use data attributes to add a table of contents and to customize calculated
values, define conditions, filters, conditional formatting properties,
and styles.
Calculated values
Create JavaScript snippets to process data attributes.
You might use these snippets to combine data attributes, trim white
space, and transform numeric values into textual descriptions. You
can process any data attribute from the current context, which includes
the query attributes of the element and the attributes from all the
parent queries of the elements.
Conditions
Use expressions that are based on
data attributes or template variables to define conditions for when
an element is to be rendered. A condition is a JavaScript expression that evaluates to
a Boolean value.
Filter versus conditions
Although filters and
conditions seem similar, they are two different mechanisms that serve
different purposes:
- A filter can be evaluated as the data is extracted from the data
source.
- A condition is evaluated only after the data is extracted from
the data source.
A condition is evaluated only once for an element, even if that
element is a query. Therefore, you cannot use the current query as
a context for a condition.
Although you can sometimes use conditions
instead of filters, using filters yields better performance because
only a subset of data is processed.
Conditional formatting
You can use expressions
to define formatting properties based on data attribute values. Conditional
formatting is similar to element conditions except that the return
values depend on the property type.