JavaScript, NodeJS & React Online Test

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?

Review the following NodeJS code:

Pick the correct statements:

A: X will be logged after Y always
B: Y will be logged after X always
C: The order of executing timeout and immediate callbacks is non-deterministic and is bound by the performance of the process
D: In this case, the function calls are scheduled in the main module and not in the I/O cycle
E: In this case, the function calls are scheduled in the I/O cycle so setImmediate is always executed before any timers scheduled in the I/O phase, independently of how many timers are left

If none of the methods (res.download, res.end, res.json, res.jsonp, res.redirect, res.render, res.send, res.sendFile, res.sendStatus) are called from a route handler to terminate request response cycle, what happens to the the client request?

A) Will be left hanging indefinitely

B) Will get an internal server error - 500 

C) Will get a service unavailable error - 503

D) Will be left hanging for a while and then request timeout error - 408

Review the following NodeJS code:

Pick the correct statements:

A: Adaface will be logged after Lovelace.
B: Lovelace will be logged after Adaface.
C: Once the asyncOpThatTakes195ms completes reading the file, it starts executing the callback which takes 10 seconds. Only after this is finished, the event loop will execute the timers that are finished. So the timeout call back will actually be executed after 205 ms even though it is scheduled to be run after 200 ms
D: Once the asyncOpThatTakes195ms completes reading the file, it starts executing the callback. While executing the callback, the scheduled timer becomes ready to be executed. So the runtime executes the timer and then completes processing the callback.

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

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 startup company E-Motors is building driverless automated cars. The car contains a sensor that checks the road quality for the next N meters to decide the optimal speed at which the cars should move. We are given recorded data by the sensor in the form of an array, where each element of the array is the rating given to 1 meter of the road in sequence. 

The rating given by the sensor is from 1 to 100, where 100 represents the road with the best condition, and any rating above 60 is optimal. Find the longest stretch of road in meters that is categorized as optimal by the sensor.

The input is an array of "strings" which needs to be converted from string to integer/number inside the function.

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.