How does event looping handle while(true) in Node.js environments?
- It blocks the event loop indefinitely, causing the application to hang.
- It executes the loop in a separate thread to avoid blocking.
- It sets a maximum execution time for the loop to prevent hanging.
- It queues the while(true) in the event loop, allowing other events to execute.
In Node.js, using while(true) will block the event loop indefinitely, causing the application to hang. This is because Node.js is single-threaded and relies on an event loop to handle asynchronous tasks. Long-running synchronous code like while(true) can prevent other tasks from being executed.
In a do-while loop, when is the condition checked?
- Before executing the code block
- After executing the code block
- During the execution of the code block
- It's not checked in a do-while loop
In a do-while loop, the condition is checked after executing the code block. This means that the code block will always execute at least once before the condition is evaluated. If the condition is true after the first execution, the loop will continue running; otherwise, it will exit. This makes do-while loops suitable when you want to ensure that a specific task is performed before checking the condition.
Imagine you’re refactoring a piece of code that involves a series of callback functions into a format that uses async/await. What should you pay extra attention to regarding error handling when refactoring the code?
- Ensure proper try/catch
- Maintain callback structure
- Avoid async/await
- Ignore error handling entirely
When refactoring code to use async/await, it's crucial to ensure proper error handling. This means using try/catch blocks around await operations to catch and handle any exceptions that may occur during asynchronous operations. Neglecting error handling could lead to unhandled exceptions and unexpected behavior.
The switch statement in JavaScript uses _________ comparison to evaluate cases.
- Strict (===)
- Loose (==)
- Greater (>)
- Lesser (<)
The switch statement in JavaScript uses strict (===) comparison to evaluate cases. This means that not only the value but also the data type must match for a case to be executed. This ensures accuracy when comparing values in a switch statement.
When using the new keyword to create an object, what kind of function must you use?
- Regular Function Declaration
- Arrow Function
- Constructor Function
- Prototype Function
When using the new keyword to create an object, you must use a Constructor Function. Constructor functions are used to create and initialize objects. They are invoked with the new keyword and often set object properties and methods within the constructor. Arrow functions are not suitable because they don't have their own this context.
Which method would you use to add a new property to an object after it has been created?
- Object.add()
- Object.append()
- Object.assign()
- Object.insert()
To add a new property to an existing object in JavaScript, you would typically use the Object.assign() method. This method allows you to merge properties from one or more source objects into a target object. It can be used to add or update properties in the target object.
What is the purpose of the this keyword inside a constructor function?
- Refers to the global object
- Refers to the parent object
- Refers to the current instance
- Refers to the next sibling
The this keyword inside a constructor function refers to the current instance of the object being created. It allows you to access and assign properties and methods to the instance being constructed, making it unique for each object created with the constructor. It does not refer to the global or parent object.
Which of the following is NOT an argument passed to an event listener when it is invoked?
- event
- target
- type
- timestamp
When an event listener is invoked, it receives an event object containing information about the event. It also has access to the target (the element that triggered the event) and type (the type of event). However, timestamp is not an argument passed to an event listener. It can be obtained using event.timeStamp.
A(n) _______ function returns a promise.
- Synchronous
- Callback
- Async
- Static
An Async function returns a promise implicitly. When you declare a function as async, it means the function will always return a promise, allowing you to use await inside it to handle asynchronous operations more cleanly.
You are writing a PHP script and you need to find the highest value in a list of numbers. How would you do this?
- max($numbers)
- min($numbers)
- sort($numbers)
- array_sum($numbers)
To find the highest value in a list of numbers in PHP, you can use the max() function. The max() function accepts an array of numbers or multiple arguments and returns the maximum value among them. This function is useful when you need to determine the highest value from a set of numbers. Learn more: https://www.php.net/manual/en/function.max.php