节流 

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    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>节流函数</title>
  </head>
  <body>
    <script>
      let a = `如果持续的去触发事件，每隔一段时间，只执行一次事件；`;
      function throttle1(func, delay) {
        let old = 0;
        return function () {
          let context = this;
          let args = arguments;
          let now = Date().now;
          if (now - old > delay) {
            func.apply(context, args);
            old = now;
          }
        };
      }
      function throttle2(func, delay) {
        let timer;
        return function () {
          let context = this;
          let args = arguments;
          if (!timer) {
            timer = setTimeout(function () {
              func.apply(context, args);
              timer = null;
            }, delay);
          }
        };
      }
      function throttle3(func, delay) {
        let timer;
        let old = 0;
        return function () {
          let context = this;
          let args = arguments;
          let now = Date().now;
          if (now - old > delay) {
            if (timer) {
              clearTimeout(timer);
              timer = null;
            }
            func.apply(context, args);
            old = now;
          } else if (!timer) {
            timer = setTimeout(function () {
              now = Date().now;
              func.apply(context, args);
              timer = null;
            }, delay);
          }
        };
      }
      function throttle4(func, delay) {
        let timer;
        let old = 0;
        return function () {
          let context = this;
          let args = arguments;
          let now = Date().now;
          if (now - old > delay) {
            if (timer) {
              clearTimeout(timer);
              timer = null;
            }
            func.apply(context, args);
            old = now;
          } else if (!timer) {
            timer = setTimeout(function () {
              now = Date().now;
              func.apply(context, args);
              timer = null;
            }, delay);
          }
        };
      }
      let a = `DOM元素的拖拽；射击游戏；计算鼠标移动的距离；监听scroll滚动；`;
    </script>
  </body>
</html>

 

posted @ 2022-05-02 18:58  苹果π  阅读(139)  评论(0)    收藏  举报