JavaScript Essentials 1 JSE1 Module 5 Test Exam Answers 100%

JavaScript Essentials 1 | JSE1 – Module 5 Test Exam Answers Full Score 100% 2024

The code snippet:
```
function test() { }
```
is:
- the declaration of the test variable in which the values returned by the completed function will be stored.
- the declaration of an empty test function.
- incorrect, as the code is wrong and does not mean anything.
- the call of the test function.
  
  Explanation & Hint:
  
  The code snippet defines a function named test without any statements inside the function body. It is an empty function.

If a function is to return some calculated value on completion, which keyword will you use to do this?

return;
ret;
yield;
function;

Explanation & Hint:

To return a calculated value from a function in JavaScript, you would use the return keyword.

The return keyword is used within a function to specify the value that should be returned when the function is called. It allows you to pass back a result or data to the caller of the function.

Analyze the code below:

function test(counter) {
    console.log("test");
    if (counter > 0)
     test(--counter);
}
test(3);

How many times will the word “`test`” be displayed in the console?

Explanation & Hint:

The code snippet will display the word “test” four times in the console. Let’s go through the code step by step:

The function test is defined, which takes a parameter named counter.
Inside the function, the string “test” is printed to the console using console.log(“test”).
Next, there is an if statement that checks if the counter variable is greater than 0.
If the counter is greater than 0, the test function is called recursively with the counter decremented by 1 (–counter). This recursive call repeats the execution of the function.
The recursive call in step 4 continues until the counter becomes 0.
When the counter reaches 0, the recursive calls stop, and the function execution completes.

Now, let’s analyze how many times the word “test” will be displayed in the console based on the code:

The initial call to test(3) is made.
Inside test(3), “test” is printed to the console.
The counter is decremented to 2, and a recursive call test(2) is made.
Inside test(2), “test” is printed to the console.
The counter is decremented to 1, and a recursive call test(1) is made.
Inside test(1), “test” is printed to the console.
The counter is decremented to 0, and a recursive call test(0) is made.
Inside test(0), “test” is printed to the console.
Since the counter is now 0, the recursive calls stop.
The execution of the function completes.

Therefore, the word “test” will be displayed in the console four times.

Analyze the following code:
```
let x = 10; 
function test() {
    let x = 20;
    console.log(x);
}
```
What will be displayed in the console as a result of its execution?
- 20
- Nothing will show up.
- x
- 10
- Explanation & Hint:
  
  Since the test function is never called in the code, the function is not executed, and therefore, nothing is printed to the console.

Review the following code:

let x = 10; 
function test(x) {
    console.log(x);
}
test(20);

What will be displayed in the console as a result of its execution?

Nothing will show up.
10
20
x

Explanation & Hint:

Let’s go through the code step by step:

A variable x is declared and initialized with the value 10 using the let keyword in the global scope.
A function named test is defined with a parameter also named x. This parameter x is a local variable within the function scope, which shadows the outer variable x.
Inside the test function, the value of the local variable x (which is the parameter) is printed to the console using console.log(x).
The function definition is complete.
The test function is called with the argument 20.

When the test function is called with the argument 20, the local variable x within the function scope takes on the value of 20. Consequently, when console.log(x) is executed inside the function, it prints 20 to the console.
Therefore, the result of executing the code will be 20 displayed in the console.

Review the following code:

let x = 10;
let y = 20;
function test(y) {
     console.log(y);
}
test(x);

What will be displayed in the console as a result of its execution?

Nothing, because the function expects the y variable to be passed and receives x instead.
20
y
10

Explanation & Hint:

The code snippet will display the value 10 in the console.

Let’s go through the code step by step:

A variable x is declared and initialized with the value 10 using the let keyword in the global scope.
A variable y is declared and initialized with the value 20 using the let keyword in the global scope.
A function named test is defined with a parameter also named y. This parameter y is a local variable within the function scope, which shadows the outer variable y.
Inside the test function, the value of the local variable y (which is the parameter) is printed to the console using console.log(y).
The function definition is complete.
The test function is called with the argument x.

When the test function is called with the argument x, the local variable y within the function scope takes on the value of the argument, which is the value of x. In this case, x is 10, so the local variable y becomes 10. Consequently, when console.log(y) is executed inside the function, it prints 10 to the console.

Therefore, the result of executing the code will be 10 displayed in the console.

You have defined a function using the following function expression:

let sum = function (a, b) {
    return (a + b);
}

What could the definition of the corresponding arrow function look like?

```
let sum = (a, b) => {
   a + b;
};
```

let sum = function (a, b) => {
    return (a + b);
}
;

```
let sum = (a, b) > a + b;
```
```
let sum = (a, b) => a + b;
```

Explanation & Hint:

The corresponding arrow function definition for the given function expression would look like: let sum = (a, b) => a + b;

In arrow functions, the syntax is more concise compared to regular function expressions. The arrow function uses the => (arrow) operator, which separates the function parameters from the function body. In this case, the arrow function takes the parameters a and b and returns their sum without explicitly using the return keyword. The result is obtained by simply expressing the addition as a + b.

The arrow function preserves the functionality of the original function expression sum but provides a more concise and expressive syntax.

The following arrow function has been defined:

let multiply = (m, n) => m * n;

How would you rewrite the function without changing what it does? Select the correct definition.

let multiply = (m, n) =>
    return (m * n);

```
let multiply = (m, n) => {
    m * n;
}
```

let multiply = (m, n) => {
    console.log(m * n);
}

let multiply = (m, n) => {
    return (m * n);
}

Explanation & Hint:

To rewrite the given arrow function without changing its functionality you would have to do this:

let multiply = (m, n) => {return (m * n);}

The multiply variable is declared using the let keyword.
It is assigned a function that takes two parameters m and n.
Inside the function body, the product of m and n is calculated using the multiplication operator *.

The calculated result is returned using the return keyword.
The function expression is terminated with a semicolon ;.

We can use the `forEach` method to pass through the elements of an array.
Which of the following code snippets will display all consecutive elements of the `animals` array in the console?

```
animals.forEach(console.log(animal));
```

forEach(animals, a => {
   console.log(a);
})

```
animals.forEach(a => a);
```

animals.forEach(a => {
    console.log(a);
})

Explanation & Hint:

Let’s analyze the code snippets one by one:

animals.forEach(console.log(animal));

This code snippet is incorrect. It directly calls console.log(animal) instead of passing a function reference or an arrow function. It will immediately execute console.log(animal) for each element of the animals array, but it won’t display the consecutive elements correctly.

animals.forEach(a => a);

This code snippet is also incorrect. The arrow function a => a doesn’t perform any action or output anything. It doesn’t contain any code to display the elements of the animals array in the console.

animals.forEach(a => { console.log(a); });

This code snippet is correct. It uses the forEach method on the animals array and provides an arrow function as the callback function. Inside the arrow function, console.log(a) is called to display each element of the animals array in the console. This will correctly display all consecutive elements of the animals array.

forEach(animals, a => { console.log(a); });

This code snippet is incorrect. It calls an undefined function forEach and tries to pass the animals array as the first argument. The correct usage is to call the forEach method directly on the array, like animals.forEach(…), as shown in snippet 3.

A `callback` function is a function that:

is passed to another function as an argument and only called in its code.
contains a reference to itself in its code.
is always executed at fixed intervals.
is always called with a certain pre-defined delay.

Explanation & Hint:

A callback function is a function that is passed as an argument to another function and is invoked or called by that function at a specific point in its execution. The primary purpose of a callback function is to provide a mechanism for executing code asynchronously or to allow behavior customization of a function.

Analyze the following code:

let show = function () {
     console.log("test");}
setTimeout(show, 2000);

What happens when you execute it?

The console to display test after a 2000-second delay.
The console to display show after a 2-second delay.
The console to display test after a 2-second delay.
The console to display test 2000 times.

Explanation & Hint:

When you execute the code, the following sequence of events will occur:

A variable named show is declared and assigned a function expression. This function has no parameters and contains a single statement that logs the string “test” to the console using console.log(“test”).
The setTimeout function is called with two arguments: the show function and a delay of 2000 milliseconds (2 seconds).
The setTimeout function is a built-in JavaScript function that schedules the execution of a function after a specified delay. In this case, it schedules the execution of the show function after a 2-second delay.
After 2 seconds have elapsed, the JavaScript runtime environment triggers the execution of the show function.
The show function is executed, and the string “test” is logged to the console using console.log(“test”).

In summary, when you execute the code, it schedules the execution of the show function to occur after a 2-second delay using setTimeout. After the specified delay, the function is executed, and “test” is displayed in the console.

JavaScript Essentials 1 | JSE1 – Module 5 Test Exam Answers Full Score 100% 2024

The code snippet:

is:

If a function is to return some calculated value on completion, which keyword will you use to do this?

Analyze the code below:

How many times will the word “test” be displayed in the console?

Analyze the following code:

What will be displayed in the console as a result of its execution?

Review the following code:

What will be displayed in the console as a result of its execution?

Review the following code:

What will be displayed in the console as a result of its execution?

You have defined a function using the following function expression:

What could the definition of the corresponding arrow function look like?

The following arrow function has been defined:

How would you rewrite the function without changing what it does? Select the correct definition.

We can use the forEach method to pass through the elements of an array. Which of the following code snippets will display all consecutive elements of the animals array in the console?

A callback function is a function that:

Analyze the following code:

What happens when you execute it?

How many times will the word “`test`” be displayed in the console?

We can use the `forEach` method to pass through the elements of an array.
Which of the following code snippets will display all consecutive elements of the `animals` array in the console?

A `callback` function is a function that: