wcag/working-examples/aria-progressbar-status-message/index.html at b39372ea5eb31e8954ad515aad5e0d3a5459b37a · w3c/wcag · GitHub

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<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8" />
    <title>
      Working example - Using an ARIA live region to convey the status of a progress bar | WCAG 2
    </title>
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <style>
      :root {
        --color-brand: #0054ae;
        --color-progress: #1e2eb8;
        background: #fff;
        color: #000;
        font: 100% / 1.5 sans-serif;
      }

      button {
        background: var(--color-brand);
        border: 1px solid transparent;
        color: #fff;
        font: inherit;
        &[aria-disabled="true"] {
          background: #e9e9e9;
          color: #696969;
          cursor: not-allowed;
        }
        &:focus-visible {
          outline: 0.125rem solid var(--color-brand);
          outline-offset: 0.125rem;
        }
      }

      .upload-container {
        max-inline-size: 25rem;
        margin-block: 1.25rem;
      }

      #upload-progress {
        --width: 0%;
        background-color: #f0f0f0;
        block-size: 1.25rem;
        border: 1px solid #808080;
        border-radius: 0.25rem;
        max-inline-size: 31.25rem;
        overflow: hidden;
        position: relative;
        &::before {
          background-color: var(--color-progress);
          block-size: 100%;
          content: "";
          inline-size: var(--width);
          inset-block-start: 0;
          inset-inline-start: 0;
          position: absolute;
          transition: inline-size 0.8s ease-in-out;
        }
        @media (prefers-reduced-motion: reduce) {
          &::before {
            transition: none;
          }
        }
      }

      #upload-progress-label {
        margin-block-end: 0;
      }

      #progress-text {
        font-size: 0.875em;
        margin: 0;
      }

      #start-upload {
        margin-block-start: 0.625rem;
        padding: 0.5rem 1rem;
      }

      .visually-hidden {
        block-size: 1px;
        border: 0;
        clip: rect(0, 0, 0, 0);
        inline-size: 1px;
        margin: -1px;
        overflow: hidden;
        padding: 0;
        white-space: nowrap;
      }
    </style>
  </head>
  <body>
    <h1>Working example - Using the ARIA <code>progressbar</code> role with a status message</h1>
    <p>
      This working example relates to
      <a href="../../techniques/aria/ARIA25.html">technique ARIA25</a>.
    </p>

    <div class="upload-container">
      <p id="upload-progress-label">Uploading document: <strong>report.pdf</strong></p>
      <div
        aria-labelledby="upload-progress-label"
        role="progressbar"
        aria-describedby="progress-text"
        aria-valuemin="0"
        aria-valuemax="100"
        aria-valuenow="0"
        id="upload-progress"
      ></div>
      <button id="start-upload" type="button">Start Upload</button>
      <div aria-live="polite" class="visually-hidden" id="progress-text">0% complete</div>
    </div>

    <script>
      (() => {
        const progressBar = document.getElementById("upload-progress");
        const progressText = document.getElementById("progress-text");
        const startButton = document.getElementById("start-upload");
        const reducedMotion = matchMedia("(prefers-reduced-motion: reduce)");

        // Non-uniform progress intervals: 0 → 15 → 35 → 70 → 90 → 100
        const steps = [
          { progress: 0, delay: 0 },
          { progress: 15, delay: 800 },
          { progress: 35, delay: 2000 },
          { progress: 70, delay: 1500 },
          { progress: 90, delay: 800 },
          { progress: 100, delay: 1800 },
        ];

        function updateProgress(stepIndex) {
          const { progress, delay } = steps[stepIndex];
          const textDelay = reducedMotion.matches ? 0 : 800;

          progressBar.ariaValueNow = progress;
          progressBar.style.setProperty("--width", `${progress}%`);

          setTimeout(() => {
            progressText.textContent = progress === 100 ? "Upload complete!" : `${progress}%`;
          }, textDelay);

          if (stepIndex + 1 < steps.length) {
            setTimeout(() => updateProgress(stepIndex + 1), steps[stepIndex + 1].delay);
          }
        }

        startButton.addEventListener("click", () => {
          if (startButton.ariaDisabled === "true") return;
          startButton.ariaDisabled = "true";
          updateProgress(0);
        });
      })();
    </script>
  </body>
</html>