custom-highlight-painting-iframe-004.html

<!DOCTYPE html>
<meta charset="UTF-8">
<title>CSS Highlight API Test: </title>
<link rel="help" href="https://drafts.csswg.org/css-highlight-api-1/">
<link rel="match" href="custom-highlight-painting-iframe-004-ref.html">
<meta name="assert" value="Creating a Highlight in the root Document with a Range in the root document and another one in an iframe is correctly painted when added to the root document's CSS.highlights (only root document's range is painted).">
<style>
  ::highlight(foo) {
    color: green;
    background-color: greenyellow;
  }
</style>
<body>
  <iframe
    id="iframe"
    srcdoc="
    <style>
      ::highlight(foo) {
        color: blue;
        background-color: cyan;
      }
    </style>
    <span id='span-iframe'>abc</span>
    "
    >
</iframe>
<br>
<span id="span-doc">abc</span>
<script>
  let spanDoc = document.querySelector("#span-doc");
  let rangeDoc = new Range();
  rangeDoc.setStart(spanDoc, 0);
  rangeDoc.setEnd(spanDoc, 1);

  let iframe = document.querySelector("#iframe");
  iframe.onload = () => {
    let spanIframe = iframe.contentDocument.querySelector("#span-iframe");
    let rangeIframe = new Range();
    rangeIframe.setStart(spanIframe, 0);
    rangeIframe.setEnd(spanIframe, 1);

    let h = new Highlight(rangeDoc, rangeIframe);
    CSS.highlights.set("foo", h);
  }
</script>

chromium/third_party/blink/web_tests/external/wpt/css/css-highlight-api/painting/custom-highlight-painting-iframe-004.html