//JavaScript Cheat Sheet 2025
//dùng Ctr + Shift + I trong trình duyệt để xem console
//xem cách cài đặt file Javascript ở menu Lập trình - Javascript
//http://www.lophocvitinh.com
//Variables
var x = 10; // Function-scoped
let y = 20; // Block-scoped
const z = 30; // Block-scoped and cannot be reassigned
//Data Types
let num = 42; // Number
let str = "Hello"; // String
let bool = true; // Boolean
let obj = { name: "John", age: 30 }; // Object
let arr = [1, 2, 3]; // Array
//Functions
function add(a, b) {
return a + b;
}
const multiply = (a, b) => a * b;
//Arrays vs Methods
let fruits = ["Apple", "Banana"];
fruits.push("Orange"); // Adds "Orange" to the end
fruits.pop(); // Removes the last element
let numbers = [1, 2, 3, 4];
let doubled = numbers.map(n => n * 2); // [2, 4, 6, 8]
//Loops
for (let i = 0; i < 5; i++) {
console.log(i);
}
let j = 0;
while (j < 5) {
console.log(j);
j++;
}
//DOM Manipulation
document.getElementById("divDemo").innerHTML = "Hello World!";
document.querySelector(".myClass").style.color = "red";
//Events
document.getElementById("btnDemo").addEventListener("click", function() {
alert("Button clicked!");
});
