say.html

<!DOCTYPE html>
<!-- saved from url=(0014)about:internet -->
<html lang="zh-cn"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title style="user-select: text !important;">信息告示</title>
  </head>
  <body>
    <div id="app">
      <label>
        告示：
        <div>
          <textarea id="display" style="width: 100%;height: 5em;"></textarea></div>
      </label>

      <button id="action" style="user-select: text !important;">加密</button>
    </div>
    <div id="tips" style="user-select: text !important;">输入文字，点击加密后，复制分享链接</div>
    <script style="user-select: text !important;">
      // https://stackoverflow.com/a/30106551
      function toBase64(string) {
        const codeUnits = new Uint16Array(string.length);
        for (let i = 0; i < codeUnits.length; i++) {
          codeUnits[i] = string.charCodeAt(i);
        }
        return btoa(String.fromCharCode(...new Uint8Array(codeUnits.buffer)));
      }
      function fromBase64(encoded) {
        const binary = atob(encoded);
        const bytes = new Uint8Array(binary.length);
        for (let i = 0; i < bytes.length; i++) {
          bytes[i] = binary.charCodeAt(i);
        }
        return String.fromCharCode(...new Uint16Array(bytes.buffer));
      }
      function removeHash() {
        history.pushState(
          "",
          document.title,
          window.location.pathname + window.location.search
        );
      }

      const setup = () => {
        const actionEl = document.getElementById("action");
        const displayEl = document.getElementById("display");
        const tipsEl = document.getElementById("tips");
        if (window.location.hash) {
          actionEl.innerText = "获取文字";
          tipsEl.innerText = "点击按钮";
          actionEl.onclick = () => {
            displayEl.value = fromBase64(window.location.hash.slice(1));
            removeHash();
            setup();
          };
        } else {
          actionEl.innerText = "加密";
          tipsEl.innerText = "输入文字，点击加密后，复制分享链接";
          actionEl.onclick = () => {
            window.location.hash = "#" + toBase64(displayEl.value);
            displayEl.value = "";
            setup();
          };
        }
      };
      setup();
    </script>
  

</body></html>