JoyceZhu.github.io/grid-testing.html at master · JoyceZhu/JoyceZhu.github.io · GitHub

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<!DOCTYPE html>
<!-- Credit to https://github.com/jscholes/jscholes.github.io/blob/master/basic-grid-activedescendant.html -->
<html lang="en">
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <title>Grid browser testing</title>

    <style>
      body {
        font-size: 100%;
        width: 100%;
        height: 100%;
      }

      table {
        margin: 1em;
        padding: 0.5em;
        border: 1px solid #000;
      }

      table:focus {
        outline: 2px solid blue;
      }

      table thead tr {
        background-color: lightgray;
      }

      table th {
        padding: 1em;
      }

      table tbody tr {
        border-bottom: 1px solid silver;
      }

      table tbody td {
        padding: 0.5em;
      }

      table tbody td:hover {
        outline: 2px dotted green;
      }

      table:focus td[data-active] {
        outline: 2px dotted blue;
      }
    </style>
  </head>

  <body>
    <h1 id="page-heading">Grid testing</h1>

    <a autofocus id="beforelink" href="#beforelink"
      >Navigate forwards from here</a
    >
    <p id="activedescendant">Basic Grid with aria-activedescendant</p>

    <table
      role="grid"
      aria-labelledby="activedescendant"
      aria-activedescendant="column-1-cell-1"
      tabindex="0"
    >
      <tr>
        <td id="column-1-cell-1">Hello</td>
        <td id="column-2-cell-1">World</td>
      </tr>
    </table>

    <p id="roving-tabindex">Basic Grid with roving tabindex</p>
    <table
      role="grid"
      aria-labelledby="roving-tabindex"
      aria-activedescendant="column-1-cell-1"
      tabindex="0"
    >
      <tr>
        <td id="column-1-cell-1">Hello</td>
        <td id="column-2-cell-1">World</td>
      </tr>
    </table>
    <a id="afterlink" href="#afterlink">Navigate backwards from here</a>

    <script id="rendered-js">
      const ARROW_LEFT = "ArrowLeft";
      const ARROW_RIGHT = "ArrowRight";

      const tableElement = document.querySelector('table[role="grid"]');

      function onGridFocus(event) {
        const activeDescendantId = tableElement.getAttribute(
          "aria-activedescendant"
        );
        const cell = document.getElementById(activeDescendantId);
        cell.dataset.active = "";
      }

      function isLeftmostCell(cell) {
        return cell.parentNode.querySelector(":first-child") === cell;
      }

      function isRightmostCell(cell) {
        return cell.parentNode.querySelector(":last-child") === cell;
      }

      function onGridKeyDown(event) {
        const activeDescendantId = tableElement.getAttribute(
          "aria-activedescendant"
        );
        const cell = document.getElementById(activeDescendantId);

        // valid key
        if (![ARROW_LEFT, ARROW_RIGHT].includes(event.key)) {
          return false;
        }

        // no modifier keys
        if (event.metaKey || event.shiftKey || event.ctrlKey) {
          return false;
        }

        if (
          (event.key === ARROW_LEFT && isLeftmostCell(cell)) ||
          (event.key === ARROW_RIGHT && isRightmostCell(cell))
        ) {
          event.preventDefault();
          event.stopPropagation();
          return false;
        }

        event.preventDefault();
        event.stopPropagation();

        delete cell.dataset.active;

        if (event.key === ARROW_LEFT) {
          tableElement.setAttribute(
            "aria-activedescendant",
            cell.previousElementSibling.id
          );
          cell.previousElementSibling.dataset.active = "";
        }

        if (event.key === ARROW_RIGHT) {
          tableElement.setAttribute(
            "aria-activedescendant",
            cell.nextElementSibling.id
          );
          cell.nextElementSibling.dataset.active = "";
        }
      }

      function init() {
        tableElement.addEventListener("focus", onGridFocus);
        tableElement.addEventListener("keydown", onGridKeyDown);
      }

      document.addEventListener("DOMContentLoaded", init);
    </script>
  </body>
</html>