Simple examples for the spread operator

basic-spread-examples.js

let myArray1 = [1,2,3]
let myString = "Hey planet!"
let myObject = {
    name: "Fernando Doglio",
    age: 35,
    country: "Uruguay",
    [Symbol.iterator]: function* () { //we're making the object iterable so we can spread it
        yield myObject.name
        yield myObject.age
        yield myObject.country
    }
}

function test() {
    console.log(arguments)
}

let splitLetters = [...myString] //no longer need for myString.split()
console.log(splitLetters)
//[ 'H', 'e', 'y', ' ', 'p', 'l', 'a', 'n', 'e', 't', '!' ]

let objLetters = {...myString}
console.log(objLetters)
/*
{ '0': 'H',
  '1': 'e',
  '2': 'y',
  '3': ' ',
  '4': 'p',
  '5': 'l',
  '6': 'a',
  '7': 'n',
  '8': 'e',
  '9': 't',
  '10': '!' }
*/
test(...myString)
/*
[Arguments] {
  '0': 'H',
  '1': 'e',
  '2': 'y',
  '3': ' ',
  '4': 'p',
  '5': 'l',
  '6': 'a',
  '7': 'n',
  '8': 'e',
  '9': 't',
  '10': '!' }
*/
//the same thing
test.call(null, ...myArray1)
//[Arguments] { '0': 1, '1': 2, '2': 3 }
test.apply(null, myArray1)
//[Arguments] { '0': 1, '1': 2, '2': 3 }

let objValues = [...myObject] //if your object is iterable, this can substitute Object.values(myObject)
console.log(objValues)
//[ 'Fernando Doglio', 35, 'Uruguay' ]

let {name, age} = {...myObject} //spread properties into individual variables
console.log("Name::", name, " age::", age)
//Name:: Fernando Doglio  age:: 35


test(...myObject) //we've turned our object into 3 different arguments
//[Arguments] { '0': 'Fernando Doglio', '1': 35, '2': 'Uruguay' }