React & Redux Online Test

A developer is working with a Redux application for managing todo items. After some changes to the code, they started facing a problem: When they try to add a new todo item, it doesn't appear on the list. However, deleting a todo item works as expected.

Here is the error message they see in the console when trying to add a todo: `Cannot read property 'undefined' of undefined.`

And here is the relevant Redux code:

Which of the following changes will resolve the issue?

A: Change payload to todo in addTodo action creator.
B: Change action.todo to action.payload in todoReducer for ADD_TODO case.
C: Change action.todo to action.payload in todoReducer for ADD_TODO case and change action.index to action.payload for DELETE_TODO case.
D: Change payload to todo in addTodo action creator and index to payload in deleteTodo action creator.

A developer is working on a Redux application where each action carries an array of items, and each item is an object with an `id` and `value`. The state is an object where each key is an item's `id` and each value is the item's `value`. However, they notice that the `ADD_ITEMS` action isn't updating the state as expected.

Here is the relevant Redux code:

What change should the developer make to correct the issue?

A developer is creating a Redux application to manage a list of blog posts. Each post is represented by an object with id, title, and content properties.

The Redux state should store the post list as an array. The developer observes that the modifications to the posts are not reflecting in the components.

Here is an example of what the state could look like:

Here is the relevant Redux code:

Which of the following changes will resolve the issue?

Review the following React code:

Pick the correct statements:

A: The code renders 10 INDIAN RUPEE
B: The code renders 10 SINGAPORE DOLLAR
C: The code does not render anything and throws an error since JavaScript objects are not valid as React children
D: When the currency portion is clicked, the parent component is re-rendered
E: When the currency portion is clicked, parent component will skip the re-render because shouldComponentUpdate returns false
F: Parent component can be converted to a functional component with memoization (useMemo or memo) to avoid the re-render

Review the following React code:

Notice that clicking on ‘Click Me’ will invoke handleClick which will throw an error. Also note that, ErrorBoundaryOne throws the error in getDerivedStateFromError. What will be rendered once ‘Click Me’ is clicked?

A: ErrorBoundaryOne will catch the error of MyComponent and <h1>C</h1> will be rendered
B: ErrorBoundaryOne will catch the error of MyComponent and its own error, <h1>C</h1> will be rendered
C: ErrorBoundaryTwo will catch the error of MyComponent and ErrorBoundaryOne, <h1>B</h1> will be rendered
D: ErrorBoundaryTwo will catch the error of MyComponent and ErrorBoundaryOne, <h1>B</h1><h1>C</h1> will be rendered
E: ErrorBoundaryTwo will catch the error of ErrorBoundaryOne. ErrorBoundaryOne will catch the error of MyComponent, <h1>B</h1> will be rendered
F: Error thrown in the click handler is not caught by any error boundary, ‘Click Me’ button will be rendered

Which of the following React code snippets
- triggers the reducer ‘rhymeReducer’ to update the ‘song’ value to ‘Jack and Jill’
- renders the updated ‘song’ value
- does not produce any errors/warnings

What will the following code output?

A: 24 after 5 seconds and after another 5 seconds, another 24
B: 24 followed by another 24 immediately
C: 24 immediately and another 24 after 5 seconds
D: After 5 seconds, 24 and 24
E: Undefined
F: NaN
G: None of these

Review the following JavaScript code and pick the correct options: 

Assume that the API returns a successful 200 response code and a JSON object as the response body. What would the value of ‘a’ be after the code is executed?

What will the output of the following JavaScript code be?

What does the following code output? 

What does the following JS code output?

We want to register students for the next semester. All students have a receipt which shows the amount pending for the previous semester. A positive amount (or zero) represents that the student has paid extra fees, and a negative amount represents that they have pending fees to be paid. The students are in a queue for the registration. We want to arrange the students in a way such that the students who have a positive amount on the receipt get registered first as compared to the students who have a negative amount. We are given a queue in the form of an array containing the pending amount.

For example, if the initial queue is [20, 70, -40, 30, -10], then the final queue will be [20, 70, 30, -40, -10]. Note that the sequence of students should not be changed while arranging them unless required to meet the condition.

⚠️⚠️⚠️ Note:
- The first line of the input is the length of the array. The second line contains all the elements of the array.
- The input is already parsed into an array of "strings" and passed to a function. You will need to convert string to integer/number type inside the function.
- You need to "print" the final result (not return it) to pass the test cases.

For the example discussed above, the input will be:
5
20 70 -40 30 -10

Your code needs to print the following to the standard output:
20 70 30 -40 -10

A manager hires a staff member to keep a record of the number of men, women, and children visiting the museum daily. The staff will note W if any women visit, M for men, and C for children. You need to write code that takes the string that represents the visits and prints the count of men, woman and children. The sequencing should be in decreasing order. 

Example:

Input:
WWMMWWCCC

Expected Output: 
4W3C2M

Explanation: 
‘W’ has the highest count, then ‘C’, then ‘M’. 

⚠️⚠️⚠️ Note:
- The input is already parsed and passed to a function.
- You need to "print" the final result (not return it) to pass the test cases.
- If the input is- “MMW”, then the expected output is "2M1W" since there is no ‘C’.
- If any of them have the same count, the output should follow this order - M, W, C.