Undefined

Question

Why does this code show undefined when I run it?

const user = {
name: 'George',
age: 31,
}

let key = 'name';

console.log (user.key);

Answer 1

You can do

user[key]
or
user.name

Answer 2

console.log (user.name);
or
console.log (key);
or
console.log (user['name']);

Good Luck
:)

Answer 3

Because user has just two properties (name and age), not key.
The value of key is a property of user.

Answer 4

user[key]

https://code.sololearn.com/W37hGD6IyXQc/?ref=app

[ ] is used when we don't know the property name in advance.

Reference:

Morpheus JS Fact Series #57:

the post:

https://www.sololearn.com/post/46592/?ref=app

his example code:

https://code.sololearn.com/WT1rPvuw28y2/?ref=app