JavaScript

JavaScript, often abbreviated as JS, is a programming language that conforms to the ECMAScript specification. JavaScript is high-level, often just-in-time compiled, and multi-paradigm. It has curly-bracket syntax, dynamic typing, prototype-based object-orientation, and first-class functions. The of this repo is to save my js programs. Basics of JavaScript. Beginner level.

Table of Contents

1. Important Methods

Methods

Most important javascript build in methods

• 1.1 typeof: Returns the type.

console.log(typeof 44); // number

console.log(typeof 'something'); // string 

console.log(typeof true); // boolean

let num = 12;
console.log(typeof(num)); // number

• 1.2 toString: Returns the string representation of the number's value.

let num = 10;
let n = num.toString();

console.log(typeof(num)); // number

console.log(typeof(n)); // string

• 1.3 indexOf: Returns the first index at which a given element can be found in the array, or -1 if it is not present.

let str = "Hello world, welcome to the JS Universe.";
console.log(str.indexOf("welcome")); // 13
console.log(str.indexOf("wall")); // -1

const fruits = ['Orange', 'Pineapple', 'Apple', 'Melon'];
console.log(fruits.indexOf('Melon')); // 3

console.log(fruits.indexOf('klkljkh')); // -1

• 1.4 lastIndexOf: Returns the last index at which a given element can be found in the array, or -1 if it is not present.

const fruits = ['Orange', 'Pineapple', 'Apple', 'Melon'];
console.log(fruits.lastIndexOf('Melon')); // 3

console.log(fruits.lastIndexOf('klkljkh')); // -1

• 1.5 length: Returns the number of characters or size in a string or array.

const fruits = ['Orange', 'Pineapple', 'Apple', 'Melon'];
console.log(fruits.length); // 4

let str = "Hello world, welcome to the JS Universe.";
console.log(str.length); // 40