webgl/webgl-tips-tabindex.html

<!-- Licensed under a BSD license. See license.html for license -->
<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
    <title>WebGL Tips - TabIndex</title>
    <style>
    .spread {
      display: flex;
      font-size: x-small;
      text-align: center;
    }
    canvas {
        margin: 5px;
        background: pink;
    }
    #c3:focus {
        outline: none;
    }
  </style>
  </head>
  <body>
    <div>click a canvas then press a key</div>
    <div class="spread">
      <div>
          <canvas width="100" height="100" id="c1"></canvas>
          <div>tabindex not set</div>
      </div>
      <div>
        <canvas width="100" height="100" id="c2" tabindex="0"></canvas>
        <div>focus style not set</div>
      </div>
      <div>
        <canvas width="100" height="100" id="c3" tabindex="1"></canvas>
        <div>tabindex and<br/>focus style set</div>
      </div>
    </div>
  </body>
<script type="module">
'use strict';

document.querySelectorAll('canvas').forEach((canvas) => {
  const ctx = canvas.getContext('2d');

  function draw(str) {
    ctx.clearRect(0, 0, canvas.width, canvas.height);
    ctx.textAlign = 'center';
    ctx.textBaseline = 'middle';
    ctx.fillText(str, canvas.width / 2, canvas.height / 2);
  }
  draw(canvas.id);

  canvas.addEventListener('focus', () => {
    draw('has focus press a key');
  });

  canvas.addEventListener('blur', () => {
    draw('lost focus');
  });

  canvas.addEventListener('keydown', (e) => {
    draw(`keyCode: ${e.keyCode}`);
  });
});

</script>
</html>