map.md

map

.map() works by returning a new array after a function has been applied to every single element in the array. Often map is used to cut down on data in deeply nested objects.

Syntax:

const newArray = someArray.map(function(element[, index, array]) {

})

Check out the docs.

Example

const numbers = [1,2,3]

function multiplyBy2 (number) {
  return number * 2;
}

const doubledNumbers = numbers.map(multiplyBy2);

console.log(doubledNumbers)
// [2, 4, 6]

Note

• .map() is syntactically similar to .forEach(). The key difference is the map returns an array, but forEach doesn't
• Like .forEach(), map takes in a callback function that can receive 3 positional parameters: element, index, container.

const numbers = [1, 2, 3, 4, 5]

const numberMultipliedByItsPositionalIndex = numbers.map(function(element, index) { 
  return element * index
})
console.log(numberMultipliedByItsPositionalIndex)
// [ 0, 2, 6, 12, 20 ]