js refer to arrow function code example

Example 1: () = javascript

//Normal function
function sum(a, b) {
  return a + b;
}

//Arraw function
let sum = (a, b) => a + b;

Example 2: () => javascript

var a = [
  "We're up all night 'til the sun",
  "We're up all night to get some",
  "We're up all night for good fun",
  "We're up all night to get lucky"
];

// Sans la syntaxe des fonctions fléchées 
var a2 = a.map(function (s) { return s.length });
// [31, 30, 31, 31]

// Avec, on a quelque chose de plus concis
var a3 = a.map( s => s.length);
// [31, 30, 31, 31]