Do Javascript Functions Always Return a Value or Implicit Undefined?

Do Javascript Functions Always Require a Return Value?

Background:

NetBeans, a code editor, automatically generates comments for Javascript functions. It includes a @returns tag with the return type {undefined} even when the function has no explicit return statement. This raises the question of whether all Javascript functions must return a specific value.

Answer:

Technically Yes:

While it may appear that a function without an explicit return statement returns nothing, the Javascript engine itself requires that every function return a value to indicate the completion of its execution. If there is no return statement, the function will implicitly return undefined.

Explicit Return Value:

Explicitly stating a return value, such as return false, is unnecessary unless the returned value is intended to be used. In other words, the return false statement is superfluous for functions that do not need to return a meaningful value.

Implicit Return Value:

Functions without an explicit return statement implicitly return undefined. This is evident when an IIFE (Immediately Invoked Function Expression) returns undefined, but the return value is typically ignored.

Why Do Functions Need to Return?

At a low level, the return statement initiates a jump command. If a function did not return anything, it would create ambiguity regarding the next function or event handler to be called.

Conclusion:

While Javascript functions may appear to function without a return statement, the Javascript engine implicitly returns undefined for such functions. Therefore, adding a return false statement is not necessary unless the function requires a specific return value.

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