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<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>closure vs event.data</title>
  <style>
    body { font-family: sans-serif; padding: 16px; max-width: 32rem; }
    h2 { font-size: 15px; margin: 16px 0 8px; }
    button { display: block; margin: 4px 0; padding: 8px 12px; cursor: pointer; }
    pre { background: #1e293b; color: #e2e8f0; padding: 12px; border-radius: 6px; font-size: 13px; white-space: pre-wrap; }
  </style>
</head>
<body>
  <h2>Without eventData (wrong)</h2>
  <div id="bad"></div>
  <h2>With event.data (correct)</h2>
  <div id="good"></div>
  <pre id="log">Click any button.</pre>
  <script src="https://code.jquery.com/jquery-3.7.1.min.js"></script>
  <script>
    var log = $("#log");
    for (var i = 0; i < 3; i++) {
      $("<button type='button'>Bad " + i + "</button>").attr("id", "bad-" + i).appendTo("#bad")
        .on("click", function () {
          log.text("bad i = " + i);
        });
      $("<button type='button'>Good " + i + "</button>").attr("id", "good-" + i).appendTo("#good")
        .on("click", { value: i }, function (event) {
          log.text("good value = " + event.data.value);
        });
    }
  </script>
</body>
</html>

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jQuery event.data — closure vs eventData (Try It)