The selectorText property of the CSSStyleRule interface gets and sets the selectors associated with the CSSStyleRule.

A string.

The CSS includes one style rule. This will be the first CSSRule returned by document.styleSheets[0].cssRules. myRules[0].selectorText therefore returns a literal string of the selector, in this case "h1".

h1 {
  color: pink;
}

let myRules = document.styleSheets[0].cssRules;
console.log(myRules[0].selectorText); // a string containing "h1".