Function Declarations vs Expressions

foo();
function foo() {
  console.log('A');
}
foo();
function foo() {
  console.log('B');
}
foo();

A, A, A
Error: foo is not a function
B, B, B
The output of this code is `B, B, B`. This demonstrates function declaration hoisting and redeclaration behavior in JavaScript. When multiple functions with the same name are declared in the same scope, the later declarations override the earlier ones. During the compilation phase, all function declarations are hoisted to the top of their scope, and in this case, the second declaration of `foo()` (which logs 'B') overwrites the first. By the time execution begins, only the last declaration of `foo` exists in memory. This is why all three calls to `foo()` log 'B'—even the first call that appears before any function declaration in the code. In strict mode and in ES6 modules, redeclaring functions like this would cause an error in some environments, but in non-strict code it leads to the last declaration winning.
A, B, B