Arrow Functions

The syntax of arrow functions that ES6 brings is a real breath of fresh air! You'll find them everywhere too - so it's important to know a few things.

parens ()

1 argument there's 1 argument, you can omit the parentheses (i.e. 'parens'), like so:

const addTwo = num => num + 2;

console.log(addTwo(2));         

0 arguments when there are no arguments, you cannot omit the parens.

const dog = () => 'Spot';

console.log(dog());         

2+ arguments when there are multiple arguments, you cannot omit the parens.

const dog = (size, name) => size + name;
console.log(dog('big','Spot'));        

curly braces {}

1 expression when your body contains just 1 expression, you can omit the curly braces.

const dog = () => 'Spot';
console.log(dog());         

1+ expressions when your body contains more than 1 expression or a statement, you must have curly braces. See here for the difference between expressions & statements.

const dog = (num) => {
  const types = ['weiner', 'lab', 'poodle'];
  return types[num];
}
console.log(dog(1));