loop key in object

// object to loop through
let obj = { first: "John", last: "Doe" };

// loop through object and log each key and value pair
//ECMAScript 5
Object.keys(obj).forEach(function(key) {
    console.log(key, obj[key]);
});

//ECMAScript 6
for (const key of Object.keys(obj)) {
    console.log(key, obj[key]);
}

//ECMAScript 8
Object.entries(obj).forEach(
    ([key, value]) => console.log(key, value)
);

Object.entries(obj).forEach(([key, value]) => {
	console.log(key, value);
});

const fruits = { apple: 28, orange: 17 }

for(key in fruits){
	console.log(key)
}

const fruits = {
  apple: 28,
  orange: 17,
  pear: 54,
}

const keys = Object.keys(fruits)
console.log(keys) // [apple, orange, pear]