for...in
Loop over plain objects ({}
).
let lunch = {
sandwich: 'ham',
snack: 'chips',
drink: 'soda',
desert: 'cookie',
guests: 3,
alcohol: false,
};
// logs "sandwich", "ham", "snack", "chips", "drink", "soda", "desert", "cookie", "guests", 3, "alcohol", false
for (let key in lunch) {
console.log(key); // key
console.log(lunch[key]); // value
}