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Barcode scanner

· 2 min read
Nam Nguyen

Sample of a barcode detector using pure html

<!DOCTYPE html>

<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>HTMX Barcode Scanner</title>
    <script src="https://unpkg.com/htmx.org@1.9.6"></script>
    <script
      type="text/javascript"
      src="https://unpkg.com/@zxing/browser@latest"
    ></script>

    <style>
      body {
        display: flex;
        flex-direction: column;
        align-items: center;
        justify-content: center;
        min-height: 100vh;
        background-color: #f3f4f6;
        padding: 1rem;
      }

      .container {
        background-color: white;
        padding: 1.5rem;
        border-radius: 0.5rem;
        box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
        text-align: center;
        width: 100%;
        max-width: 600px;
      }

      .title {
        font-size: 1.5rem;
        font-weight: bold;
        color: #4a5568;
        margin-bottom: 1rem;
      }

      .scanner-container {
        position: relative;
        width: 100%;
        height: 13rem;
        border: 4px solid #4299e1;
        border-radius: 0.5rem;
        overflow: hidden;
      }

      video {
        width: 100%;
        height: 100%;
        object-fit: cover;
      }

      .result {
        margin-top: 1rem;
        color: #718096;
      }

      .result span {
        font-weight: 600;
        color: #4299e1;
      }

      .error-message {
        margin-top: 0.5rem;
        color: #f56565;
        display: none;
      }

      .button {
        margin-top: 1rem;
        padding: 0.5rem 1rem;
        border-radius: 0.5rem;
        color: white;
        cursor: pointer;
        box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
      }

      .button:disabled {
        cursor: not-allowed;
        opacity: 0.5;
      }

      .start-button {
        background-color: #4299e1;
      }

      .start-button:hover:not(:disabled) {
        background-color: #3182ce;
      }

      .stop-button {
        background-color: #e53e3e;
      }

      .stop-button:hover:not(:disabled) {
        background-color: #c53030;
      }
    </style>
    <script type="module">
      const video = document.getElementById("scanner");
      const resultSpan = document.getElementById("result");
      const errorMessage = document.getElementById("error-message");
      const startButton = document.getElementById("start-button");
      const stopButton = document.getElementById("stop-button");
      let scanner;
      let controls;

      async function startScanner() {
        try {
          const stream = await navigator.mediaDevices.getUserMedia({
            video: { facingMode: "environment" },
          });
          video.srcObject = stream;
          video.play();
          errorMessage.style.display = "none";
          scanner = new ZXingBrowser.BrowserMultiFormatReader();
          const previewElem = document.getElementById("scanner");

          let lastResult = null;
          let lastDecodeTime = 0;
          const debounceTime = 5000; // 5 seconds

          const videoInputDevices =
            await ZXingBrowser.BrowserCodeReader.listVideoInputDevices();
          const selectedDeviceId = videoInputDevices[0].deviceId;

          controls = await scanner.decodeFromVideoDevice(
            selectedDeviceId,
            previewElem,
            (result, err) => {
              const currentTime = Date.now();
              if (
                result &&
                result.text !== lastResult &&
                currentTime - lastDecodeTime > 1000
              ) {
                // 1 second debounce time
                lastResult = result.text;
                lastDecodeTime = currentTime;
                resultSpan.innerText = result.text;
                stopScanner(); // Stop the scanner and video stream after a successful scan
              }
              if (err) {
                console.log("err", err);
                console.log("No barcode detected...");
              }
            }
          );

          startButton.disabled = true;
          stopButton.disabled = false;
        } catch (err) {
          console.log("error", error);
          errorMessage.innerText =
            "Camera access denied. Please enable camera permissions.";
          errorMessage.style.display = "block";
        }
      }

      function stopScanner() {
        try {
          if (scanner) {
            controls.stop();
            stopButton.disabled = true;
            startButton.disabled = false;
          }
        } catch (error) {
          console.log("error", error);
        }
      }
      startButton.addEventListener("click", startScanner);
      stopButton.addEventListener("click", stopScanner);
    </script>
  </head>

  <body>
    <div class="container">
      <h2 class="title">Barcode Scanner</h2>

      <div class="scanner-container">
        <video id="scanner" autoplay></video>
      </div>

      <p class="result">Scanned Code: <span id="result"></span></p>

      <p id="error-message" class="error-message"></p>

      <button id="start-button" class="button start-button">
        Start Scanner
      </button>
      <button id="stop-button" class="button stop-button" disabled>
        Stop and Reset Scanner
      </button>
    </div>
  </body>
</html>