11. Void

The void type is used to indicate that a function does not return any value, or a variable should not have any usable value.

Example 1: Function Returning void

function warnUser(): void {
  console.log("This is my warning message");
}

• The void return type signifies that the warnUser function does not return anything (it just performs an action, like logging a message).

Example 2: Assigning void to a Variable

let unusable: void = undefined;
unusable = null;  // OK if `--strictNullChecks` is not enabled

• A variable with the void type can only be assigned undefined or null.
• If --strictNullChecks is not enabled, null is also allowed as a valid value for void.

Key Points:

• void is typically used as the return type of functions that don’t return a value.
• Variables with the void type can hold undefined or null, but only under certain compiler settings.