# # `macro()`

The macro method lets you register custom methods

    collect().macro("uppercase", function() {
      return this.map(function(item) {
        return item.toUpperCase();
      });
    });

    const collection = collect(["a", "b", "c"]);

    collection.uppercase();

    collection.all();

    //=> ['A', 'B', 'C']

> Note that the `macro` method returns `undefined`, and therefore it is not possible to use it within a chain of methods.

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