arrow_functions_exercise.md

Arrow Functions Exercise

In this exercise, you’ll refactor some ES5 code into ES2015.

ES5 Map Callback

function double(arr) {
	return arr.map(function(val) {
	return val * 2;
	});
}

ES2015 Arrow Functions Shorthand

Refactor the above code to use two arrow functions. Turn it into a one-liner.

/* Write an ES2015 Version */
const double = arr => arr.map(val => val * 2);

Refactor the following function to use arrow functions:

Replace ALL functions with arrow functions:

function squareAndFindEvens(numbers){
	var squares = numbers.map(function(num){
	return num ** 2;
	});
	var evens = squares.filter(function(square){
	return square % 2 === 0;
	});
	return evens;
}

Solution:

const squareAndFindEvens = numbers => numbers.map(num => num ** 2).filter(square => square % 2 === 0);

Solution

See Our solution.