The Error of Getting an Object Element in JavaScript

Let's say we have some object:

let obj = {
	a: 1,
	b: 2,
	c: 3,
	d: 4,
	e: 5,
};

Let's say we want to get an element from this object by a certain key. Let the name of this key be entered by the user into an input:

console.log(input.value);

Some beginner programmers make the following mistake: they iterate over the object in a loop, comparing the keys one by one with the input value, like this:

for (let key in obj) {
	if (key === input.value) {
		let elem = obj[key];
		console.log(elem); // the desired value
		break;
	}
}

However, in this task, the loop is completely unnecessary. After all, we can simply get our value by key, like this:

let elem = obj[input.value];

If necessary, you can add a check for the presence of such a key in the object:

if (obj[input.value] !== undefined) {
	let elem = obj[input.value];
	console.log(elem);
} else {
	console.log('no such key in the object');
}