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<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>then → catch</title>
</head>
<body>
  <h1>then() → catch()</h1>
  <button id="ok">Resolve</button>
  <button id="bad">Reject</button>
  <pre id="out"></pre>
  <script src="https://code.jquery.com/jquery-3.7.1.min.js"></script>
  <script>
    function run(shouldSucceed) {
      var lines = [];
      var dfd = $.Deferred();

      dfd
        .then(function (result) {
          lines.push("then: " + result);
          return result;
        })
        .catch(function (error) {
          lines.push("catch: " + error);
        });

      if (shouldSucceed) {
        dfd.resolve("profile loaded");
      } else {
        dfd.reject("404 Not Found");
      }

      document.getElementById("out").textContent = lines.join("\n");
    }

    $("#ok").on("click", function () { run(true); });
    $("#bad").on("click", function () { run(false); });
  </script>
</body>
</html>

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jQuery deferred.catch() — then / catch chain (Try It)