Function Expressions

A function expression stores a function as a value.

This is useful when passing functions into methods such as .map() and .filter().

Function Declaration

const numbers = [1, 2, 3, 4, 5, 6]
const squares = numbers.map(square)
 
function square(element) {
  return element ** 2
}
 
console.log(squares)

Function Expression

const numbers = [1, 2, 3, 4, 5, 6]
 
const squares = numbers.map(function (element) {
  return element ** 2
})
 
const evenNumbers = numbers.filter(function (element) {
  return element % 2 === 0
})
 
const oddNumbers = numbers.filter(function (element) {
  return element % 2 !== 0
})
 
console.log(squares)
console.log(evenNumbers)
console.log(oddNumbers)