The loop for-in is intended to iterate
over objects. It has the following syntax:
for (let variableForKey in object) {
}
In variableForKey the keys of the iterated
object will fall sequentially. Let's try with some
example. Suppose we have such an object:
let obj = {a: 1, b: 2, c: 3};
Let's use the loop for-in to
derive the keys of this object:
for (let key in obj) {
console.log(key); // shows 'a', 'b', 'c'
}
Now let's get the elements:
for (let key in obj) {
console.log(obj[key]); // shows 1, 2, 3
}
Print all the keys of the following object to the console:
let obj = {x: 1, y: 2, z: 3};
Print all the elements of the following object to the console:
let obj = {x: 1, y: 2, z: 3};