All questions of Functions for Software Development Exam

Explanation:

Function Definitions:
- The code defines two functions, add and multiply, which perform addition and multiplication operations respectively.

Calculation:
- The add function takes two parameters a and b and returns their sum.
- The multiply function takes two parameters a and b and returns their product.
- In the expression add(2, multiply(3, 4)), the multiply function is called first with arguments 3 and 4, resulting in the product 12.
- Then, the add function is called with arguments 2 and 12, resulting in the sum 14.

Output:
- The final value 14 is stored in the variable result.
- The code then prints the value of result using console.log.
- Therefore, the output of the code will be 24.

Explanation:
When the above code is executed, it will output "undefined" in the console.

Reasoning:
To understand why "undefined" is the output, let's break down the code step by step:

1. The function outer() is defined.
2. Inside the outer() function, a variable x is declared and assigned a value of 10.
3. The function inner() is defined.
4. Inside the inner() function, a console.log(x) statement is executed. At this point, the variable x is still in the temporal dead zone (TDZ) since it has been declared but not yet assigned a value.
5. Next, the variable x is declared and assigned a value of 20. This assignment happens after the console.log(x) statement.
6. Finally, the inner() function is invoked.

Hoisting and Scoping:
The reason why the code outputs "undefined" instead of 10 is due to a concept called hoisting and the scoping rules in JavaScript.

- Hoisting: JavaScript moves all variable and function declarations to the top of their respective scopes during the creation phase. However, only the declarations are hoisted, not the assignments. In our code, the variable x is hoisted to the top of the inner() function, but its assignment of 20 is not hoisted.
- Scoping: JavaScript has function-level scoping. This means that variables declared inside a function are only accessible within that function, not outside. In our code, the variable x inside the inner() function shadows the variable x in the outer() function.

Order of Execution:
1. When the inner() function is invoked, the console.log(x) statement is executed. At this point, the variable x is in the TDZ and has not been assigned a value yet, so it is undefined.
2. After the console.log(x) statement, the variable x is assigned a value of 20.
3. Since the variable x inside the inner() function only exists within the function's scope, it does not affect the variable x in the outer() function.
4. Finally, when the outer() function is invoked, it calls the inner() function, which outputs "undefined" to the console.

Therefore, the correct answer is option C) Undefined.

Function greet() { console.log("Hello World!"); }

greet();

The output will be "Hello World!"

Explanation:
- The code snippet provided defines a function called `outer()` that contains a variable `x` with a value of 10.
- Inside the `outer()` function, there is another function called `inner()` that simply logs the value of `x` to the console.
- The `inner()` function is then returned from the `outer()` function.
- The line `var closureFn = outer();` invokes the `outer()` function and assigns the returned `inner()` function to the variable `closureFn`.
- Finally, the line `closureFn();` calls the `inner()` function stored in the `closureFn` variable.

Output:
The output of the code will be `10`.

Explanation:
- When the `inner()` function is returned from the `outer()` function, it forms a closure.
- A closure is a combination of a function and the lexical environment within which that function was declared.
- In this case, the `inner()` function has access to the variable `x` from its parent function `outer()`, even after the `outer()` function has finished executing.
- When the `closureFn()` function is called, it executes the `inner()` function and logs the value of `x` to the console, which is `10`.
- This is because the `inner()` function maintains a reference to its outer environment, including the variable `x`.
- Therefore, the value of `x` is accessible to the `inner()` function even though it is no longer in scope.
- This behavior is characteristic of closures in JavaScript, where functions retain access to variables from their containing scope even after the outer function has completed execution.

Explanation:

Initial Setup:
- The variable x is declared and assigned a value of 5.
- A function named updateX is defined, which updates the value of x to 10.

setTimeout Function:
- The setTimeout function is used to delay the execution of the updateX function by 1000 milliseconds (1 second).

Console Logging:
- The value of x is logged to the console before the setTimeout function has a chance to execute the updateX function.

Output:
- As the updateX function is executed after a delay of 1 second, the value of x remains 5 when it is logged to the console.
- Therefore, the output of the code will be 5.