If a function is defined twice, what will happen when the function is called?

In programming languages such as JavaScript, when a function is defined multiple times with the same name, the most recent declaration will be the one that takes effect. This means that when the function is called, it will execute the code contained in the second declaration.

Essentially, the language will overwrite the previous definition with the new one, which is why the last declaration is the one that is invoked upon calling the function. This can lead to confusion if the earlier versions have different logic or purposes, but in terms of execution, only the last one will be recognized and executed.

This behavior can lead to bugs if the programmer is not aware of how function declarations are managed because any earlier versions of the function will be lost, replaced by the final version. Understanding this concept is important for managing code effectively, especially in larger projects where functions may be declared in different scopes or files.