A function declaration is hoisted to the top of the ________ in which it was defined.
- Scope
- Block
- Function
- Statement
A function declaration is hoisted to the top of the function in which it was defined. This means you can use a function before declaring it in your code, but it's important to understand the implications of hoisting for variable scoping.
The method _______ is used to sort the elements of an array.
- sort()
- splice()
- split()
- reduce()
The correct method is sort(). JavaScript arrays have a built-in sort() method that is used to sort the elements of an array in ascending order by default. You can also provide a compare function to customize the sorting behavior. For example, myArray.sort((a, b) => a - b) sorts the array numerically.
You're refactoring your code to improve performance and notice a function that returns another function, accessing variables outside of its own scope. What specific JavaScript concept should you consider when optimizing this code section?
- Function Closures
- Function Prototypes
- Event Bubbling
- AJAX (Asynchronous JavaScript and XML)
When optimizing code that returns a function and accesses variables outside of its own scope, you should consider the concept of function closures. Function closures allow an inner function to "remember" and access variables from its containing (parent) function's scope even after the parent function has finished executing. This can be useful for encapsulating state and optimizing code.
The arithmetic operator _______ increments the value of a variable by 1.
- ++
- --
- +
- +=
The arithmetic operator '++' is known as the increment operator. It increases the value of a variable by 1. For example, if you have a variable x and you write x++, it will increment the value of x by 1. This is commonly used in loops and counters in JavaScript.
Which of the following JavaScript methods can create a new HTML element?
- createElement()
- createNode()
- createTag()
- newElement()
You can create a new HTML element in JavaScript using the createElement() method. This method is used to dynamically generate HTML elements in your code. It takes the name of the HTML tag you want to create as an argument.
While reading through a JavaScript codebase, you see a function that is returned from another function and retains access to its lexical scope, even after the outer function has finished execution. What is this pattern called?
- Callback
- Promise
- IIFE (Immediately Invoked Function Expression)
- Higher-order Function
This pattern is known as a "Higher-order Function." In JavaScript, higher-order functions are functions that can take other functions as arguments or return them. This enables functions to maintain access to their lexical scope, creating closures.
What is the purpose of the status property in an HTTP response?
- To specify the content type
- To indicate the HTTP status
- To define the response data
- To specify the request method
The status property in an HTTP response is used to indicate the HTTP status code for the response. HTTP status codes provide information about the outcome of an HTTP request, such as whether it was successful (e.g., status code 200 for OK) or encountered an error (e.g., status code 404 for Not Found). It helps the client understand the result of the request.
You are debugging a JavaScript application and encounter a ReferenceError at runtime, despite a function being defined in the code. What could be the possible reason if the function was defined using a function expression?
- The function is declared within a block scope.
- The function was defined in strict mode.
- The function was hoisted to the top of the code.
- The function was defined inside another function.
When a function is defined using a function expression and declared within a block scope, it may not be accessible outside of that block, resulting in a ReferenceError. This is because the function's scope is limited to the block where it's defined.
When dealing with callbacks, the first argument is traditionally
- Callback
- Error
- Function
- Result
When dealing with callbacks, the first argument is traditionally reserved for Error. This convention allows developers to handle errors gracefully when executing asynchronous operations. It helps in proper error handling and prevents unexpected crashes in your code.
How does the browser determine the path along which the event propagates?
- Bubbling phase and capturing phase both follow the DOM hierarchy from the target element to the document root.
- It is determined by the order in which event listeners were added.
- The browser chooses a random path for event propagation.
- It follows the DOM hierarchy from the document root to the target element.
The browser determines the path of event propagation based on the DOM hierarchy. Events can propagate in two phases: capturing and bubbling. In the capturing phase, events travel from the document root to the target element. In the bubbling phase, events travel from the target element back up to the document root. This order ensures that ancestors and descendants of the target element have an opportunity to handle the event.