file_window_print.html

Enable keyboard shortcuts

<!doctype html>

<meta charset="utf-8">

<div id="before-print">Before print</div>

<canvas id="canvas" width="100" height="100"></canvas>

<script>

  onload = function() {

    // window.print() is special until after the load event is finished firing.

    setTimeout(function() {

      // This fires a timer which would trigger a navigation and prevent the

      // test from completing if it happens during window.print().

      let meta = document.createElement("meta");

      meta.setAttribute("http-equiv", "refresh");

      meta.setAttribute("content", "0; url=/unlikely-to-be-found");

      document.head.appendChild(meta);

      // This one should block until we're done printing, and block the

      // navigation too.

      window.print();

      meta.remove();

      document.body.insertAdjacentHTML('beforeend', `<div id="after-first-print">After first print</div>`);

      let canvas = document.getElementById("canvas");

      canvas.mozPrintCallback = function() {};

      // This one shouldn't, because the print callbacks need to run.

      window.print();

      document.body.insertAdjacentHTML('beforeend', `<div id="after-second-print">After second print</div>`);

    }, 0);

</script>