class reference
Expression.<class name>
The class reference expression uses a syntax from CSS selectors to reference all elements with a given class. It typically evaluates to a NodeList of all matching classes, unless it is used as the right hand side of an assignment.
<div _="on click add .clicked">Add the .clicked class to me!</div>
<div _="on click log .clicked">
Log all elements with the clicked class on it in the DOM
</div>