Javascript Code Snippets

let age = 25;

let name = "John";

let isStudent = true;

let address;

let salary = null;

let sym = Symbol("id");

let bigIntNumber = 1234567890123456789012345678901234567890n;

console.log(0 / 0); // NaN console.log(parseInt("abc")); // NaN

console.log(typeof a);

class gfg { constructor(name, estd, rank) { this.n = name; this.e = estd; this.r = rank; } decreaserank() { this.r -= 1; } } const test = new gfg("tom", 2009, 43); test.decreaserank(); console.log(test.r); console.log(test);

class car { constructor(brand) { this.carname = brand; } present() { return 'I have a ' + this.carname; } } class Model extends car { constructor(brand, model) { super(brand); super.present(); this.model = model; } show() { return this.present() + ', it is a ' + this.model; } }

class car { constructor(brand) { this.carname = brand; } // Getter method get cnam() { return "It is " + this.carname; // Return a value } // Setter method set cnam(x) { this.carname = x; } } const mycar = new car("Ford"); console.log(mycar.cnam);

(function() { console.log("IIFE executed!"); })();

function higherOrderFunction(callback) { return callback(); } function sayHello() { return "Hello!"; } console.log(higherOrderFunction(sayHello)); // "Hello!"

var name = "John"; function sayName() { console.log(name); var name = "Jane"; } sayName();

document.getElementById("elementId");

document.getElementsByClassName("className");

document.getElementsByTagName("tagName");

document.querySelector(".className"); document.querySelectorAll(".className");

function changeValue(x) { x = 10; console.log("Inside function:", x) } let num = 5; changeValue(num);

function changeProperty(obj) { obj.name = "Alice"; console.log("Inside function:", obj.name); // Output: Inside function: Alice } let person = { name: "Bob" }; changeProperty(person); console.log("Outside function:", person.name); // Output: Outside function: Alice

"use strict"; x = 10; // Throws an error because x is not declared

function sum(a, b, c) { return a + b + c; } const numbers = [1, 2, 3]; console.log(sum(...numbers)); // Output: 6

class Animal { constructor(name) { this.name = name; } } class Dog extends Animal { constructor(name, breed) { super(name); this.breed = breed; } } const myDog = new Dog('Buddy', 'Golden Retriever'); console.log(myDog instanceof Dog); // true console.log(myDog instanceof Animal); // true console.log(myDog instanceof Object); // true console.log(myDog instanceof Array); // false

const numbers = [1, 2, 3, 4, 5, 6]; const evenNumbers = numbers.filter(num => num % 2 === 0); console.log(evenNumbers); // [2, 4, 6]

const numbers = [1, 2, 3, 4, 5]; const sum = numbers.reduce((sum, value) => sum + value, 0); // sum = 0 initially console.log(sum); // 15

function sum(...numbers) { return numbers.reduce((sum, value) => sum + value, 0); } console.log(sum(1, 2, 3)); // 6 console.log(sum(5, 10, 15, 20)); // 50

function myFunction() { x = 10; // no error }

const PI = 3.14;

let c=1; let c=3;// throws error let count = 0; if (true) { let count = 1; console.log(count); // Output: 1 } console.log(count); // Output: 0

var name = 'John'; if (true) { var name = 'Doe'; console.log(name); // Output: Doe } console.log(name); // Output: Doe console.log(a) var a=2 // prints undefined

import React from 'react'; class MyComponent extends React.Component { handleClick = (event) => { // `event` is a SyntheticEvent console.log(event.type); // Always 'click' regardless of browser console.log(event.target); // Consistent target property } render() { return Click Me; } }

console.log(x); // Output: undefined var x = 5; console.log(x); // Output: 5 // Function hoisting hoistedFunction(); // Output: "Hoisted!" function hoistedFunction() { console.log("Hoisted!"); } // Function expressions are not hoisted notHoisted(); // Error: notHoisted is not a function var notHoisted = function() { console.log("Not hoisted"); };

let result = 5 + "10"; // "510" let result = "5" * 2; // 10 let result = "5" - 2; // 3 let result = "5" / 2; // 2.5

let num = 5; let str = String(num); // "5" let str2 = num.toString(); // "5" let str3 = `${num}`; // "5"

// Parent Component function Parent() { const data = "Hello from Parent!"; return ; } // Child Component function Child(props) { return 
{props.message}
; }

// Function Component using useState import { useState } from 'react'; function Counter() { const [count, setCount] = useState(0); return ( 
 
Count: {count}
  setCount(count + 1)}>Increment 
 ); }

function outerFunction(outerVariable) { return function innerFunction(innerVariable) { console.log('Outer Variable:', outerVariable); console.log('Inner Variable:', innerVariable); }; } const newFunction = outerFunction('outside'); newFunction('inside');

function add(a) { return function(b) { return a + b; }; } const add5 = add(5); console.log(add5(3)); // Output: 8 console.log(add(2)(3)); // Output: 5

function* generateSequence() { yield 1; yield 2; yield 3; } const generator = generateSequence(); console.log(generator.next()); // { value: 1, done: false } console.log(generator.next()); // { value: 2, done: false } console.log(generator.next()); // { value: 3, done: false } console.log(generator.next()); // { value: undefined, done: true }