Function Types

Now that we know how to define a function and how to use a function, we can take a look at other ways we can make functions.

There are 3 kinds of functions.

Function Types

Function Declaration

This is also called Function Statement

function myFunc() {
  return 'some value'
}

This is the most normal way of declaring functions, and you are going to use most of these.

Function Expression

This is also called Function Literal

const myFunc = function optionalName() {
  return 'some value'
}

A function expression have to be declared first before you can call them. These can be without a name like the example bellow. These are called anonymous function expression.

const myFunc = function () {
  return 'some value'
}

Arrow Function

Arrow functions are a part of the “new” ES6 JavaScript.

const myFunc = () => {
  return 'some value'
}

const myFunc2 = (name, age) => {
  return 'My name is ' + name + ' and my age is ' + age
}

These are the same as the anonymous function expression but instead of having a keyword function before the parentheses, they have the arrow sign after =>.

But if you are going to only return just some value back you can skip the { } curly brackets and the return keyword.

const myFunc2 = (name, age) => {
  return 'My name is ' + name + ' and my age is ' + age
}

// is the same as

const myFunc2 = (name, age) => 'My name is ' + name + ' and my age is ' + age

There are some differences between these 3 way of declaring the functions.

I like to use the arrow function as much as I can when I bind them to an object, and I like the function declaration when is just alone.