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<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>Lodash _.once basic</title>
</head>
<body>
  <h1>Once initializer</h1>
  <pre id="out"></pre>
  <script src="https://cdn.jsdelivr.net/npm/lodash@4.17.21/lodash.min.js"></script>
  <script>
    (function () {
      var runs = 0;
      var loadConfig = _.once(function () {
        runs += 1;
        return { apiUrl: "https://example.test", runs: runs };
      });
      var first = loadConfig();
      var second = loadConfig();
      document.getElementById("out").textContent = JSON.stringify({
        runsCounter: runs,
        sameReference: first === second,
        first: first,
        second: second
      }, null, 2);
    })();
  </script>
</body>
</html>

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Lodash _.once — one-time side effect (Try It)