map.md

chapter	6
pageNumber	49
description	The map method iterates over an array and modifies its element using a callback function. This callback function is applied to each element of the array.

Map

The Array.prototype.map() method iterates over an array and modifies its elements using a callback function. The callback function will then be applied to each element of the array.

Here's the syntax for using map.

let newArray = oldArray.map(function(element, index, array) {
  // element: current element being processed in the array
  // index: index of the current element being processed in the array
  // array: the array map was called upon
  // Return element to be added to newArray
});

For example, let's say you have an array of numbers and you want to create a new array that doubles the values of the numbers in the original array. You could do this using map like this.

const numbers = [2, 4, 6, 8];

const doubledNumbers = numbers.map(number => number * 2);

console.log(doubledNumbers);

// Result: [4, 8, 12, 16]

You can also use the arrow function syntax to define the function passed to map.

let doubledNumbers = numbers.map((number) => {
  return number * 2;
});

or

let doubledNumbers = numbers.map(number => number * 2);

{% hint style="info" %} The map() method doesn't execute function for empty elements and doesn't change the original array. {% endhint %}