1. The void type
In a way, void is like the opposite of any; it has no type at all. When a function returns no value, you usually see the return value of type void.
- Note: Declaring a variable of type void is useless because its value can only be undefined or null
2.Null and Undefined
In TypeScript, undefined and null have their own types undefined and NULL, respectively.
3. Never type
The never type represents the types of values that never exist. For example, the never type is the return type of function expressions or arrow function expressions that always throw an exception or have no return value at all.