boz
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billd-live


			
				
					
						
						
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    <meta charset="UTF-8" />
    <meta
      name="viewport"
      content="width=device-width, initial-scale=1.0"
    />
    <title>Document</title>
  </head>
  <body>
    <script>
      /**
       * @param {number} targetCount 不小于1的整数，表示经过targetCount帧之后返回结果
       * @return {Promise<number>}
       */
      const getScreenFps = (() => {
        // 先做一下兼容性处理
        const nextFrame =
          window.requestAnimationFrame ||
          window.webkitRequestAnimationFrame ||
          window.mozRequestAnimationFrame;
        if (!nextFrame) {
          console.error('requestAnimationFrame is not supported!');
          return;
        }
        return (targetCount = 120) => {
          // 判断参数是否合规
          if (targetCount < 1)
            throw new Error('targetCount cannot be less than 1.');
          const beginDate = Date.now();
          let count = 0;
          return new Promise((resolve) => {
            (function log() {
              nextFrame(() => {
                if (++count >= targetCount) {
                  const diffDate = Date.now() - beginDate;
                  const fps = (count / diffDate) * 1000;
                  return resolve(fps);
                }
                log();
              });
            })();
          });
        };
      })();
      getScreenFps().then((res) => {
        console.log(res);
      });
    </script>
  </body>
</html>