JavaScript Internals (521 Qs)•Part 2: Promises, Callbacks, Async & Strict Mode (54 - 103)
What is undefined property
The undefined property indicates that a variable has not been assigned a value, or declared but not initialized at all. The type of undefined value is undefined too.
javascript
var user; // Value is undefined, type is undefined
console.log(typeof user); //undefined
Any variable can be emptied by setting the value to undefined.
javascript
user = undefined;