网页FPS查看

317 阅读1分钟

直接将下列代码复制粘贴即可

const showFPS = (function () {

  // noinspection JSUnresolvedVariable, SpellCheckingInspection
  const requestAnimationFrame =
      window.requestAnimationFrame || // Chromium
      window.webkitRequestAnimationFrame || // Webkit
      window.mozRequestAnimationFrame || // Mozilla Geko
      window.oRequestAnimationFrame || // Opera Presto
      window.msRequestAnimationFrame || // IE Trident?
      function (callback) { // Fallback function
         window.setTimeout(callback, 1000 / 60);
      };
  let dialog;
  let container;
  let fps = 0;
  let lastTime = Date.now();
  function setStyle(el, styles) {
    for (const key in styles) {
      el.style[key] = styles[key];
    }
  }

  function init() {
    dialog = document.createElement('dialog');
    setStyle(dialog, {
      display: 'block',
      border: 'none',
      backgroundColor: 'rgba(0, 0, 0, 0.6)',
      margin: 0,
      padding: '4px',      position: 'fixed',
      top: 0,
      right: 'auto,',
      bottom: 'auto',
      left: 0,
      color: '#fff',
      fontSize: '12px',
      textAlign: 'center',
      borderRadius: '0 0 4px 0'
    });
    container.appendChild(dialog);
  }

  function calcFPS() {
    let offset = Date.now() - lastTime;
     fps += 1;
    if (offset >= 1000) {
      lastTime += offset;
      displayFPS(fps);
      fps = 0;
    }
    requestAnimationFrame(calcFPS);
  }

  function displayFPS(fps) {
    const fpsStr = `${fps} FPS`;
    if (!dialog) {
      init();
    }
    if (fpsStr !== dialog.textContent) {
      dialog.textContent = fpsStr;
    }
  }
  return function (parent) {
    container = parent;
    calcFPS();
  };
}());
showFPS(document.body);