What is the concept of Array.map?

Question

I am having problems understanding the concept of Array.map. I did go to Mozilla and Tutorials Point, but they provided very limited info regarding this.

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Answer 1

Summary

Array.map is a function which is located on Array.prototype.map. The function does the following:

1. Creates a new array with the same amount of entries/elements.
2. Executes a callback function, this function receives and current array element as an argument and returns the entry for the new array.
3. Returns the newly created array.

Example:

Basic usage:

const array = [1, 2, 3, 4];

// receive each element of array then multiply it times two
// map returns a new array
const map = array.map(x => x * 2);

console.log(map);

The callback function also exposes an index and the original array:

const array = [1, 2, 3, 4];

// the callback function can also receive the index and the 
// original array on which map was called upon
const map = array.map((x, index, array) => {
  console.log(index);
  console.log(array);
  return x + index;
});

console.log(map);