JavaScript Complete Guide

1. Introduction

JavaScript is used to make websites interactive and dynamic.

console.log("Hello World");

2. Variables

let name = "Sasank";
const age = 18;
var city = "India";

3. Data Types

let x = 10;       // number
let y = "text";   // string
let z = true;     // boolean

4. Operators

let sum = 5 + 3;
let isEqual = (5 == "5");

5. Conditions

let age = 18;

if(age >= 18){
  console.log("Adult");
}else{
  console.log("Minor");
}

6. Loops

for(let i=0; i<5; i++){
  console.log(i);
}

7. Functions

function greet(name){
  return "Hello " + name;
}

console.log(greet("Sasank"));

8. Arrays

let arr = [1,2,3];

arr.forEach(x => console.log(x));

9. Objects

let user = {
  name: "Sasank",
  age: 18
};

console.log(user.name);

10. DOM Manipulation

document.getElementById("btn").onclick = function(){
  alert("Clicked!");
};

11. Events

button.addEventListener("click", function(){
  console.log("Clicked");
});

12. Fetch API

fetch("https://api.github.com/users")
  .then(res => res.json())
  .then(data => console.log(data));