JavaScript basics

//-------------------------------------------

/REST operator

function sum(...numbers) {

  console.log("Performing addition of", numbers);

  let sumofnums = 0;

  numbers.forEach(function (item) {

    sumofnums += item;

  });

  return sumofnums;

}

console.log("Sum of 3 numbers: ", sum(1, 2, 3));

console.log("Sum of 5 numbers: ", sum(1, 2, 3, 4, 5));

function createTeam(teamName, captain, ...members) {

  return {

    name: teamName,

    captain: captain,

    members: members,

  };

}

const team = createTeam("Avengers", "Iron Man", "Thor", "Hulk", "Black Widow");

console.log(team);

const colors = ["red", "green", "blue", "yellow", "purple"];

const [primaryColor, secondaryColor, ...otherColors] = colors;

console.log("Primary color:", primaryColor);

console.log("Secondary color", secondaryColor);

console.log("Other colors:", otherColors);

//REST operator with object de-structuring

const person = {

  name: "Sarah",

  age: 28,

  city: "Chicago",

  job: "Developer",

  hobbies: ["reading", "hiking"],

};

const { name, age, ...otherDetails } = person;

console.log("Name", name);

console.log("age", age);

console.log("Other details", otherDetails);

//---------------------------------------------

//Spread operator

//expanding arrays

const numbers = [1, 2, 3, 4, 5];

console.log(...numbers);

//combining arrays

const fruits = ["apple", "orange"];

const vegetables = ["carror", "potato"];

const produce = [...fruits, ...vegetables];

console.log(produce);

//copying arrays

const copyNumbers = [...numbers, 6, 7, 8];

console.log(copyNumbers);

//copying objects

const person = { name: "Alex", age: 30 };

const personCopy = { ...person };

console.log(personCopy);

//adding properties while copying

const personCopyAndAdd = { ...person, hobby: "reading", age: 31 };

console.log(personCopyAndAdd);

//---------------------------------------------------

//Truthy and Falsy

// the && operator returns the first falsy operand, or the last truthy if all operands are truthy.

console.log(true && "Hello");

console.log(true && "hi" && "Hello"); //returning the last truthy operand

console.log(false && "Hello");

console.log(false && 0 && "Hello"); // returning the first falsy operand

console.log("" && "Hello");

console.log(0 && "Hello");

//Javascript has exactly six falsy values, everything else is truthy

//false         //boolean

//0             //the number 0

//''            //Empty string ('' or "")

//null          //absence of any value

//undefined     //uninitialized variable

//NaN           //not a number

//The || operator returns the first truthy operand or the last falsy operand if all the operands are falsy

console.log(true || "Hello");

console.log(false || "Hello");

console.log(0 || "" || null || "Default");

console.log(0 || "" || null || undefined);

//-----------------------------------------------------