The keyText property of the CSSKeyframeRule interface represents the keyframe selector as a comma-separated list of percentage values. The from and to keywords map to 0% and 100%, respectively.

A string.

SyntaxError

Thrown if keyText is updated with an invalid keyframe selector, in which case keyText remains untouched.

The CSS includes a keyframes at-rule. This will be the first CSSRule returned by document.styleSheets[0].cssRules. myRules[0] returns a CSSKeyframesRule object, which will contain individual CSSKeyFrameRule objects for each keyframe.

@keyframes slidein {
  from {
    transform: translateX(0%);
  }

  to {
    transform: translateX(100%);
  }
}

let myRules = document.styleSheets[0].cssRules;
let keyframes = myRules[0]; // a CSSKeyframesRule
console.log(keyframes[0].keyText); // a string containing 0%