Calls a function for each element of the array and returns a new array of results
.map() is one of the most useful and used iterator methods
.map() is does NOT mutate the original array
The callback function for .map() accepts the following parameters:
currentValue: (required) current element being processed in the array.
index: (optional) index of the current element being processed in the array
array: (optional) the array map was called upon.
Using traditional (ES5) function syntax
const result = arr.map(function(item, index, array) {
// returns the new value instead of item
})
Using arrow syntax (ES6)
const result = arr.map((item, index, array) => {
// returns the new value instead of item
})
const numbers = [1, 2, 3, 4, 5 ]
const numbersSquared = numbers.map((number) => {
return number**2
})
console.log(numbersSquared) // [2, 4, 9, 16, 25]
console.log(numbers) // [1, 2, 3, 4, 5 ]
.map() to downcase all the words in loudWords. Save the returned values to a variable declared with const called lowerCaseWords;