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  <title>Lodash _.mapKeys - collisions</title>
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  <h1>_.mapKeys - silent collisions</h1>
  <pre id="out"></pre>
  <script src="https://cdn.jsdelivr.net/npm/lodash@4.17.21/lodash.min.js"></script>
  <script>
    (function () {
      var fruits = { apple: 1, avocado: 2, banana: 3 };
      var collide = _.mapKeys(fruits, function (value, key) {
        return key[0];
      });
      var safe = _.mapKeys(fruits, function (value, key) {
        return key[0] + "_" + key;
      });
      var grouped = Object.keys(fruits).reduce(function (acc, key) {
        var bucket = key[0];
        if (!acc[bucket]) acc[bucket] = [];
        acc[bucket].push({ key: key, value: fruits[key] });
        return acc;
      }, {});
      var lines = [
        "key[0]              : " + JSON.stringify(collide),
        "key[0] + '_' + key  : " + JSON.stringify(safe),
        "manual group        : " + JSON.stringify(grouped)
      ];
      document.getElementById("out").textContent = lines.join("\n");
    })();
  </script>
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