Function Declarations vs Expressions

The function is only defined if the condition is true
It's treated as a function expression and assigned to a variable
It causes a syntax error because function declarations aren't allowed in blocks
It creates a function in the enclosing function or global scope, regardless of the condition
Traditionally in JavaScript, when you create a function declaration inside an if statement or any block, it creates a function in the enclosing function or global scope, regardless of the condition. This is because function declarations were historically hoisted to their containing function or global scope, not block scope. However, this behavior is considered problematic and inconsistent across browsers, which is why it's specified as undefined behavior in ECMAScript specifications. Modern JavaScript environments (with strict mode or ES6) have more consistent behavior, but it's still best practice to avoid function declarations inside blocks. If you need conditional function creation, use function expressions with appropriate variables: `if (condition) { const myFunc = function() { ... }; }`. This creates a function only when the condition is true and binds it to a block-scoped variable, which is more predictable and maintainable.