ES6 Arrow Functions - 1

MAP applies a function to every array element and returns a new array

const names=[‘john’,’katy perry’];

const fullNames=names.map(function(name){return `${name} Mayer`;});

//using an arrow function (concise)

const fullNames2=names.map((name)=>{return `${name} Mayer`;});

//If one parameter, can omit parantheses

const fullNames3=names.map(name=>{return `${name} Mayer`;})

//If no parameters, use empty brackets ()

const fullNames5=names.map(()=>`cool Mayer`);

//If returning, can omit braces (Implicit return)

const fullNames4=names.map(name=>`${name} Mayer`);

//If returning an object expression, wrap object in ()

const race=“100m Dash”;

const winners=names.map(winner=>({name:winner, race}));

//two parameters

const winners=names.map((winner,i)=>({name:winner,position:i+1,race}));

//Arrow functions are anonymous, cannot be stack traced

FILTER returns an array of terms that result in an expression to true

const ages=[11,54,45,34,65,72,23,17];

const young=ages.filter(function(age){return age<18});

//with arrow function

const young2=ages.filter(age=>age<18);