The matches read-only property of the MediaQueryList interface is a boolean value that returns true if the document currently matches the media query list, or false if not.

You can be notified when the value of matches changes by watching for the change event to be fired at the MediaQueryList.

A boolean value that is true if the document currently matches the media query list; otherwise, it's false.

This example detects viewport orientation changes by creating a media query using the orientation media feature:

const mql = window.matchMedia("(orientation:landscape)");
mql.addEventListener("change", (event) => {
  if (event.matches) {
    console.log("Now in landscape orientation");
  } else {
    console.log("Now in portrait orientation");
  }
});

• Media queries
• Using media queries from code
• window.matchMedia()
• MediaQueryList
• MediaQueryListEvent