spread params javascript code example

Example 1: spread operator in javascript

// spread operators can be used for arrays or objects

// cloning to prevent mutation.
let numList = [1,2,3];
let numListClone = [...numList]; // [1, 2, 3]

// spread operator for destructuring.
let animal = {
  name: 'dog',
  color: 'brown',
  age: 7
};
let { age, ...otherProperties } = animal; 

// spread operator as rest operator
function sum(x, y, ...rest) {}

// spread operator for merging arrays or objects
let numLists = [...numList1, ...numList2];
let animalWithBreed = {
  ...animal,
  breed: '',
}

Example 2: spread and rest operator javascript

var myName = ["Marina" , "Magdy" , "Shafiq"] ;const [firstName , ...familyName] = myName ;console.log(firstName); // Marina ;console.log(familyName); // [ "Magdy" , "Shafiq"] ;

Example 3: js spread parameters

// seperate each element of array using ...
let list = ['a','b','c'];
let copy = [...list, 'd', 'e']; // ['a', 'b', 'c', 'd', 'e']
//use for infinite parameters to a function
function toDoList(...todos) {
  //todos is an array, so it has map function
  document.write(
    `<ul>${todos.map((todo) => `<li>${todo}</li>`).join("")}</ul>`
  );
}
toDoList("wake up", "eat breakfast", ...list); //ul containing: wake up eat breakfast a b c

Example 4: spread and rest operator javascript

function myData(...args){console.log(args) ; // ["Marina",24,"Front-End Developer"]}myData("Marina",24,"Front-End Developer") ;