Intro.js

/* This is a comment
    that spans multiple lines
    */

    // This is a single-line comment

    var first = 0;
    var First = 0;
    var str = "Hello World!"; // String variable
    var bool = true; // Boolean variable
    var num = 42; // Number variable
    var arr = [1, 2, 3]; // Array variable
    var obj = { name: "John", age: 30 }; // Object variable
    var func = function() { // Function variable
        console.log("Hello from function!");
    };
    var nullVar = null; // Null variable
    var num;

    console.log(first,obj); // Output: 0 { name: "John", age: 30 }
    console.log(str); // Output: Hello World!

    // == Equality operator
    // === Strict equality operator
    // != Inequality operator
    // !== Strict inequality operator
    // > Greater than operator
    // < Less than operator
    // >= Greater than or equal to operator
    // <= Less than or equal to operator
    // && Logical AND operator
    // || Logical OR operator
    // ! Logical NOT operator
    // ++ Increment operator
    // -- Decrement operator
    // += Addition assignment operator
    // -= Subtraction assignment operator
    // *= Multiplication assignment operator
    // /= Division assignment operator
    // %= Modulus assignment operator

    // ** Exponentiation operator
    // << Left shift operator
    // >> Right shift operator
    // >>> Unsigned right shift operator
    
    // & Bitwise AND operator
    // | Bitwise OR operator
    // ^ Bitwise XOR operator
    // ~ Bitwise NOT operator
const PI=3.14; // Constant variable
const E=2.71; // Constant variable
const GRAVITY=9.81; // Constant variable    
const SPEED_OF_LIGHT=299792458; // Constant variable



// 
//PI = 3067. // Error: Assignment to constant variable.
// E = 2.72; // Error: Assignment to constant variable.
// GRAVITY = 9.8; // Error: Assignment to constant variable.
// SPEED_OF_LIGHT = 300000000; // Error: Assignment to constant variable.

console.log(PI); // Output: Hello World!

var car = {
    make: "Toyota",
    model: "Camry",
    year: 2020,
    start: function() {
        console.log("Car started!");
    }
};

car.start(); // Output: Car started!

var person = {
    name: "John",
    age: 30,
    greet: function() {
        console.log("Hello, my name is " + this.name);
    }
};

person.greet(); // Output: Hello, my name is John