const obj = { a: 1, b: 2, c: 3 }; 
const result = Object.keys(obj).map((key) => [key, obj[key]]);

let x = 10; 
function foo() { 
let x = 20; 
console.log(x); 
} 
foo(); 
console.log(x);

const arr = [1, 2, 3, 4, 5]; 
const sum = arr.reduce((acc, val) => acc + val, 0);

const promise1 = new Promise((resolve, reject) => { 
setTimeout(resolve, 500, 'one'); 
}); 
const promise2 = new Promise((resolve, reject) => { 
setTimeout(resolve, 100, 'two'); 
}); 
Promise.race([promise1, promise2]).then((value) => { 
console.log(value); 
});

class Person { 
constructor(name) { 
this.name = name; 
} 
sayHello() { 
return `Hello, ${this.name}`; 
} 
}

function* generator() { 
yield 1; 
yield 2; 
yield 3; 
} 
const gen = generator(); 
console.log(gen.next().value); 
console.log(gen.next().value); 
console.log(gen.next().value); 
console.log(gen.next().value);