A map is a data collection type where data is stored in the form of pairs. It contains a unique key. The value stored in the map must be mapped to the key. We cannot store a duplicate pair in the map(). It is because of the uniqueness of each stored key. It is mainly used for fast searching and looking up data.
In the given example, the map() function takes an array of numbers and double their values. We assign the new array returned by map() to the variable doubleValue and log it.
In React, the map() method used for:
1. Traversing the list element.
2. Traversing the list element with keys.