let map = new Map();  
map.set("name", "Ali");  
console.log(map.get("name")); // "Ali"  
map.delete("name");  
console.log(map.has("name")); // false 

let ws = new WeakSet();  
let obj = {name: "Ali"};  
ws.add(obj);  
console.log(ws.has(obj)); // true  
ws.delete(obj);

let wm = new WeakMap();  
let obj = {};  
wm.set(obj, "Ma'lumot");  
console.log(wm.get(obj)); // "Ma'lumot"  
wm.delete(obj);

let arr = [1, 2, 3, 4, 5];  
arr.push(6); // Oxiriga qo'shadi  
arr.pop(); // Oxirgi elementni o'chiradi  
arr.filter(x => x > 2); // 2dan kattalarini oladi

let str = "JavaScript";  
console.log(str.length); // 10  
console.log(str.toUpperCase()); // "JAVASCRIPT"  
console.log(str.replace("Script", "Lang")); // "JavaLang"

let obj = {name: "Ali", age: 25};  
console.log(Object.keys(obj)); // ["name", "age"]  
console.log(Object.values(obj)); // ["Ali", 25]  
console.log(Object.entries(obj)); // [["name", "Ali"], ["age", 25]]

let arr1 = [1, 2, 3];  
let arr2 = [...arr1, 4, 5];  
console.log(arr2); // [1, 2, 3, 4, 5]  

let obj1 = {a: 1, b: 2};  
let obj2 = {...obj1, c: 3};  
console.log(obj2); // {a: 1, b: 2, c: 3}

function sum(...numbers) {  
  return numbers.reduce((a, b) => a + b, 0);  
}  
console.log(sum(1, 2, 3, 4)); // 10

let myPromise = new Promise((resolve, reject) => {  
  setTimeout(() => resolve("Ma'lumot keldi!"), 2000);  
});  

myPromise.then(data => console.log(data));