What is a composite selector in Angular?

A composite selector in Angular refers to a selector that combines conditions such as elements and attributes, allowing for more specific targeting of DOM elements. This type of selector is particularly useful when you want to apply styles or logic to elements that meet multiple criteria simultaneously, providing a more nuanced selection than simply targeting by element type or attribute alone.

For instance, a composite selector could be used to select all <div> elements that also have a specific attribute (like [appDirective]). This enables developers to apply styles or Angular features specifically to a subset of elements, enhancing both maintainability and performance.

Using composite selectors helps developers create more modular and reusable components by ensuring that their styles and behavior are precisely applied where intended, rather than broadly affecting all instances of a particular type. This selective targeting is essential in large applications where elements may share common types but require different handling based on additional criteria.