# Iterator — Iterator helper methods

> > [!NOTE] > These methods are _iterator_ helpers, not _iterable_ helpers, because the only requirement for an object to be iterable is just the presence of a Symbol.iterator method.

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&gt; [!NOTE] &gt; These methods are _iterator_ helpers, not _iterable_ helpers, because the only requirement for an object to be iterable is just the presence of a Symbol.iterator method. There is no shared prototype to install these methods on.

The Iterator class itself provides some helper methods for working with iterators. For example, you may be tempted to do the following

This first converts the iterator returned by {{jsxref("Map.prototype.values()")}} to an array, then uses the {{jsxref("Array.prototype.reduce()")}} method to calculate the sum. However, this both creates an intermediate array and iterates the array twice. Instead, you can use the reduce() method of the iterator itself

This method may be more efficient, especially memory-wise, because it only iterates the iterator once, without memorizing any intermediate values. Iterator helper methods are necessary to work with infinite iterators

You cannot convert seq to an array, because it is infinite. Instead, you can use the find() method of the iterator itself, which only iterates seq as far as necessary to find the first value that satisfies the condition.

You will find many iterator methods analogous to array methods, such as

{{jsxref("Iterator.prototype.drop()")}} and {{jsxref("Iterator.prototype.take()")}} combined are somewhat analogous to {{jsxref("Array.prototype.slice()")}}.

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