When working with TypeScript, developers may come across the terms "never" and "void" while defining function return types. Both types signify the absence of a return value, but subtle differences exist between them.
"Void" is a type that represents the absence of a value returned by a function. It means that the function will execute but not return any data. It is useful when we want to perform some side-effect, like logging a message or updating a database, without returning any data.
On the other hand, "never" is a type that represents a function that will never return. It means the function will throw an error or enter into an infinite loop. It is useful when we want to signal that a function will never complete normally.
Consider the following examples:
In the example above,
logMessage is a function that logs a message to the console and returns nothing, so its return type is
throwError is a function that throws an error, so its return type is
infiniteLoop is a function that enters into an infinite loop and never returns, so its return type is also
In summary, "void" is used when a function performs a side-effect and does not return any data, while "never" is used when a function will never complete normally. Understanding the differences between these types is important to use them correctly in your TypeScript code.