function factorial(n) { // Base case: factorial of 0 or 1 is 1 if (n === 0 || n === 1) { return 1; } else { // Recursive case: n! = n * (n-1)! return n * factorial(n - 1); } } // Example usage: const result = factorial(5); console.log(result); // Output: 120 function factorialIterative(n) { let result = 1; for (let i = 2; i <= n; i++) { result *= i; } return result; } const result1 = factorialIterative(6); console.log(result1); // Output: 720 function factorialTernary(n) { return (n === 0 || n === 1) ? 1 : n * factorialTernary(n - 1); } const result2 = factorialTernary(4); console.log(result2); // Output: 24 function factorialWhileLoop(n) { let result = 1; while (n > 1) { result *= n; n--; } return result; } const result3 = factorialWhileLoop(4); console.log(result3); // Output: 24 const factorialES6 = n => (n === 0 || n === 1) ? 1 : n * factorialES6(n - 1); const result4 = factorialES6(5); console.log(result4); // Output: 120 const factorialES6Iterative = (n, result = 1) => { for (let i = 2; i <= n; i++) { result *= i; } return result; }; const result5 = factorialES6Iterative(5); console.log(result5); // Output: 120 const factorialES6Reduce = n => [...Array(n).keys()].reduce((acc, val) => acc * (val + 1), 1); const result6 = factorialES6Reduce(6); console.log(result6); //720 const factorialMemoized = (function() { const memo = {}; function factorial(n) { if (n === 0 || n === 1) { return 1; } // Check if the result is already memoized if (memo[n]) { return memo[n]; } // Calculate and memoize the result memo[n] = n * factorial(n - 1); return memo[n]; } return factorial; })(); // Example usage: const result7 = factorialMemoized(5); console.log(result7); // Output: 120 const factorialFunctional = n => Array.from({ length: n }, (_, i) => i + 1).reduce((acc, val) => acc * val, 1); const result8 = factorialFunctional(5); console.log(result8); // Output: 120 //------------------------------------ const compose = (...functions) => input => functions.reduceRight((acc, fn) => fn(acc), input); const range = n => Array.from({ length: n }, (_, i) => i + 1); const multiply = (a, b) => a * b; const factorialComplex = n => compose( result => console.log(result), // Display the result (optional) numbers => numbers.reduce(multiply, 1), // Multiply all numbers in the array range, // Generate an array of numbers from 1 to n )(n); //----------------------- const factorialUsingMap = n => { return Array.from({ length: n }, (_, i) => i + 1) .map(number => BigInt(number)) // Convert numbers to BigInt to handle larger factorials .reduce((acc, val) => acc * val, BigInt(1)); }; // Example usage: const result9 = factorialUsingMap(5); console.log(result9.toString()); // Output: 120 const factorialUsingIIFEES6 = ((n) => { const calculateFactorial = (num, result = BigInt(1)) => { if (num === 0 || num === 1) { return result; } return calculateFactorial(num - 1, result * BigInt(num)); }; return calculateFactorial(n); })(5); // Pass the desired input to the IIFE console.log(factorialUsingIIFEES6.toString()); // Output: 120
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Javascript(JS) is a object-oriented programming language which adhere to ECMA Script Standards. Javascript is required to design the behaviour of the web pages.
var readline = require('readline');
var rl = readline.createInterface({
input: process.stdin,
output: process.stdout,
terminal: false
});
rl.on('line', function(line){
console.log("Hello, " + line);
});
Keyword | Description | Scope |
---|---|---|
var | Var is used to declare variables(old way of declaring variables) | Function or global scope |
let | let is also used to declare variables(new way) | Global or block Scope |
const | const is used to declare const values. Once the value is assigned, it can not be modified | Global or block Scope |
let greetings = `Hello ${name}`
const msg = `
hello
world!
`
An array is a collection of items or values.
let arrayName = [value1, value2,..etc];
// or
let arrayName = new Array("value1","value2",..etc);
let mobiles = ["iPhone", "Samsung", "Pixel"];
// accessing an array
console.log(mobiles[0]);
// changing an array element
mobiles[3] = "Nokia";
Arrow Functions helps developers to write code in concise way, it’s introduced in ES6.
Arrow functions can be written in multiple ways. Below are couple of ways to use arrow function but it can be written in many other ways as well.
() => expression
const numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
const squaresOfEvenNumbers = numbers.filter(ele => ele % 2 == 0)
.map(ele => ele ** 2);
console.log(squaresOfEvenNumbers);
let [firstName, lastName] = ['Foo', 'Bar']
let {firstName, lastName} = {
firstName: 'Foo',
lastName: 'Bar'
}
const {
title,
firstName,
lastName,
...rest
} = record;
//Object spread
const post = {
...options,
type: "new"
}
//array spread
const users = [
...adminUsers,
...normalUsers
]
function greetings({ name = 'Foo' } = {}) { //Defaulting name to Foo
console.log(`Hello ${name}!`);
}
greet() // Hello Foo
greet({ name: 'Bar' }) // Hi Bar
IF is used to execute a block of code based on a condition.
if(condition){
// code
}
Else part is used to execute the block of code when the condition fails.
if(condition){
// code
} else {
// code
}
Switch is used to replace nested If-Else statements.
switch(condition){
case 'value1' :
//code
[break;]
case 'value2' :
//code
[break;]
.......
default :
//code
[break;]
}
For loop is used to iterate a set of statements based on a condition.
for(Initialization; Condition; Increment/decrement){
//code
}
While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.
while (condition) {
// code
}
Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.
do {
// code
} while (condition);
ES6 introduced classes along with OOPS concepts in JS. Class is similar to a function which you can think like kind of template which will get called when ever you initialize class.
class className {
constructor() { ... } //Mandatory Class method
method1() { ... }
method2() { ... }
...
}
class Mobile {
constructor(model) {
this.name = model;
}
}
mbl = new Mobile("iPhone");