how to declare arrow function in javascript code example

Example 1: how to make javascript function consise

multiplyfunc = (a, b) => { return 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]

Example 3: concise body arrow functions javascript

const plantNeedsWater = day => day === 'Wednesday' ? true : false;

//If only 1 Parameter no () needed
//Single line return is implicit
//Single line no {} needed