console 命令行工具 X clear
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<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      * {
        padding: 0;
        margin: 0;
      }
      html,
      body {
        width: 100%;
        height: 100%;
        display: flex;
        flex-direction: column;
      }
      body > div {
        margin: auto;
        display: flex;
        flex-direction: column;
      }
    </style>
  </head>
  <body>
    <div>
      <input type="text" />
      <span></span>
    </div>
  </body>
  <script>
      /**
      *
      * func立即执行，之后每wait间隔执行，最后还会执行一次
      */
    function throttle(func, wait) {
      var play = false;
      var copy = func;
      return function () {
        var context = this;
        var args = arguments;
        copy = func;
        if (!play) {
          if (copy) {
            copy.call(this, ...arguments);
            copy = null;
          }
          play = true;
          let timer = setTimeout(function() {
            play = false;
            if (copy) {
              copy.call(context, ...args);
            }
            clearTimeout(timer);
          }, wait);
        }
      };
    }
    const div = document.getElementsByTagName("div")[0];
    div.children[0].addEventListener(
      "input",
      throttle((e) => {
        div.children[1].innerHTML = e.target.value;
      }, 2000)
    );
  </script>
</html>