The item() method of the MediaList interface returns the media query at the specified index, or null if the specified index doesn't exist.

index

An integer.

If the bracket ([]) syntax is used and there is no entry for the given index, undefined is returned.

The following would log to the console each media query stored in the MediaList associated with the first stylesheet applied to the current document.

const stylesheet = document.styleSheets[0];
console.log(stylesheet.media.length);
console.log(stylesheet.media.item(0)); // Returns a string like "print"
console.log(stylesheet.media.item(5)); // Returns null if there is no 5th entry
console.log(stylesheet.media[1]); // Returns a string like "print"
console.log(stylesheet.media[5]); // Returns undefined if there is no 5th entry