The read-only style property of the CSSFontFaceRule interface returns the style information from the @font-face at-rule. This will be in the form of a CSSStyleDeclaration object.

A CSSStyleDeclaration.

This example uses the CSS found as an example on the @font-face page. The first CSSRule returned will be a CSSFontFaceRule. The style property returns a CSSStyleDeclaration with the properties fontFamily, fontWeight, and src populated with the information from the rule.

@font-face {
  font-family: MyHelvetica;
  src: local("Helvetica Neue Bold"), local("HelveticaNeue-Bold"),
    url(MgOpenModernaBold.ttf);
  font-weight: bold;
}

let myRules = document.styleSheets[0].cssRules;
console.log(myRules[0].style); //a CSSStyleDeclaration