First Class Functions Javascript

• What are First Class Functions?
  • In a language where a function can be treated like a variable their functions are called first class functions
  • Functions can be passed into another functions, can be used, manipulated & returned, basically, anything a variable can do, a function can also do.

function square (num) {
	return num * num;
}

function displaySquare(fn) {
	console.log("Square is " + fn(5));
}

displaySquare(square); // function square is passed in another function displaySquare