You want to select an element with the ID 'special' using JavaScript. However, your code isn't working as expected. What could be the possible reason if the HTML structure is correct?

  • Typo in the ID selector
  • Missing JavaScript library inclusion
  • The element is hidden by CSS
  • Case sensitivity issues
If your code to select an element by its ID isn't working, one possible reason could be a typo in the ID selector. IDs are case-sensitive, so make sure it matches the ID attribute in the HTML exactly. The other options are less likely causes: missing libraries would generally cause JavaScript errors, and CSS hiding doesn't affect element selection.

What will the for...of loop iterate over in an array?

  • Indexes of the array
  • Property names of the array
  • Values of the array
  • The array itself
The for...of loop is used to iterate over the values of an array, making it useful for accessing the elements directly. Unlike the for...in loop, which iterates over properties, for...of provides a simple way to loop through the contents of an array.

How can you add a new item to the beginning of an array?

  • arr.unshift(newItem);
  • arr.push(newItem);
  • arr.append(newItem);
  • arr.insert(0, newItem);
To add a new item to the beginning of an array in JavaScript, you can use the arr.unshift(newItem); method. This will insert newItem at the start of the array, shifting the existing elements to the right. push() adds to the end of the array, append() and insert() are not standard array methods.

Which HTTP status code represents a successful GET request?

  • 200
  • 300
  • 400
  • 500
The HTTP status code '200' indicates a successful GET request. It means that the request was received, understood, and the server has responded with the requested data. Other status codes like 300 (redirect), 400 (client error), and 500 (server error) signify different types of issues or responses. Understanding status codes is crucial for handling HTTP requests properly in JavaScript.

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.

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.

What is a practical use of closures in JavaScript?

  • Encapsulation
  • Inheritance
  • Code Reusability
  • Memory Management
Closures in JavaScript are often used for encapsulation. They allow variables and functions to be "enclosed" within a function, preventing them from polluting the global scope and providing a level of data privacy. This enables code organization, reduces naming conflicts, and promotes modularity in your programs. Closures are a key feature in achieving encapsulation in JavaScript.

How can you prevent script injection attacks when dynamically modifying element content with user input?

  • Use the innerText property to set the content.
  • Use the innerHTML property to set the content.
  • Use a library like jQuery to sanitize input data.
  • Use textContent property to set the content.
To prevent script injection attacks, it's crucial to use the textContent property to set content dynamically. Unlike innerHTML, which parses and executes scripts, textContent treats input as plain text, reducing the risk of script injection. Using libraries may help but doesn't guarantee security. innerText has limited browser support.

How can you select all

elements within a specific parent element?

  • document.getElementsByTagName('p')
  • document.select('p')
  • document.querySelectorAll('p')
  • parentElement.querySelectorAll('p')
To select all

elements within a specific parent element, you can use the querySelectorAll() method on the parent element. This method allows you to specify the CSS selector within the context of the parent element, ensuring that only

elements within that parent are selected. The other options are incorrect for this purpose.

The _________ method is used to bind an object context to a function and is called immediately.

  • Bind
  • Apply
  • Call
  • Invoke
The "call" method in JavaScript is used to bind an object's context to a function and is called immediately. It allows you to specify the value of "this" explicitly when invoking a function, along with any additional arguments you want to pass to the function.

How does an arrow function handle the "this" keyword differently than regular functions?

  • Arrow functions inherit the "this" value from their containing scope.
  • Arrow functions have their own "this" context.
  • Arrow functions automatically bind "this" to the global object.
  • Arrow functions can't use "this" keyword.
Arrow functions behave differently from regular functions when it comes to the "this" keyword. They inherit the "this" value from their containing lexical (surrounding) scope, while regular functions have their "this" determined by how they are called. This behavior can be advantageous in certain situations.

How can you handle exceptions within a "for" loop to prevent it from being terminated prematurely?

  • By wrapping the entire loop in a try-catch block
  • By using the "continue" statement
  • By adding a "finally" block after the loop
  • By setting a maximum execution time for the loop
To handle exceptions within a "for" loop, you can wrap the entire loop in a try-catch block. This allows you to catch and handle exceptions that occur during the loop's execution, preventing it from being terminated prematurely. The other options do not directly address exception handling within the loop.