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Question 1. What does AJAX stand for in web development? A) Automated JavaScript and XML B) Asynchronous JavaScript and XML C) Advanced Java Application XML D) Array JavaScript and XHTML Answer: B Explanation: AJAX stands for Asynchronous JavaScript and XML, describing a technique for making asynchronous web requests. Question 2. Which core technology is used to initiate an AJAX request? A) HTML B) CSS C) JavaScript D) PHP Answer: C Explanation: JavaScript is responsible for triggering and handling AJAX requests within the browser. Question 3. Which object is primarily used for AJAX requests in most browsers? A) Window B) XMLHttpRequest C) Document D) FormData Answer: B Explanation: XMLHttpRequest is the standard browser API for making AJAX requests. Question 4. What is the main advantage of AJAX over traditional web interactions?
A) Faster server response times B) Partial page updates without full reload C) Automatic data encryption D) Pre-loading all resources Answer: B Explanation: AJAX allows updating parts of a webpage without requiring a full refresh. Question 5. Which property of XMLHttpRequest indicates the request is complete and response is ready? A) status B) readyState = 4 C) responseText D) open Answer: B Explanation: A readyState of 4 means the AJAX request is finished, and response data is available. Question 6. What does the 'open()' method of XMLHttpRequest specify? A) Type of data to send B) URL, HTTP method, and async/sync flag C) Server response type D) Data encoding format Answer: B Explanation: The open() method defines the HTTP method, target URL, and whether the request is asynchronous. Question 7. Which method is used to send the AJAX request after configuration?
B) JSON
C) CSV
D) TXT
Answer: B Explanation: JSON (JavaScript Object Notation) is commonly used for lightweight data exchange. Question 11. How do you parse a JSON string received from an AJAX response? A) JSON.convert() B) JSON.decode() C) JSON.parse() D) parseJSON() Answer: C Explanation: JSON.parse() is the correct method to convert a JSON string to a JavaScript object. Question 12. Which method can be used to convert a JavaScript object to a JSON string before sending data? A) stringifyObject() B) JSON.stringify() C) objectToJSON() D) parseToJSON() Answer: B Explanation: JSON.stringify() serializes a JavaScript object into a JSON string. Question 13. What is the main role of the DOM in AJAX programming? A) Handling network connections B) Manipulating webpage content dynamically
C) Encrypting server data D) Storing cookies Answer: B Explanation: The DOM allows for dynamic updates to the webpage after receiving AJAX responses. Question 14. Which method is used to set custom HTTP headers in an XMLHttpRequest? A) setHeader() B) setRequestHeader() C) addHeader() D) customHeader() Answer: B Explanation: setRequestHeader() is used to set custom headers for AJAX requests. Question 15. What argument can be used in the open() method to make an AJAX request synchronous? A) true B) false C) "sync" D) 1 Answer: B Explanation: Passing false as the last argument makes the request synchronous. Question 16. Which JavaScript method retrieves the value of an HTML element by its ID? A) querySelector() B) getElementById() C) getElementsByClassName()
Answer: B Explanation: onreadystatechange triggers whenever the readyState changes. Question 20. What does the FormData API provide in AJAX? A) Form validation B) Simplified handling of multipart/form data C) JSON conversion D) DOM manipulation Answer: B Explanation: FormData simplifies sending multipart/form-data, including file uploads, via AJAX. Question 21. What is the purpose of the query string in GET requests? A) It holds server response data B) It encodes parameters in the URL C) It defines HTTP headers D) It formats the HTML Answer: B Explanation: The query string appends parameters to the URL in GET requests. Question 22. Which method in jQuery is used for fetching JSON data? A) $.get() B) $.post() C) $.getJSON() D) $.ajaxSetup() Answer: C
Explanation: $.getJSON() is specifically designed to retrieve JSON data. Question 23. How does AJAX enhance User Experience (UX)? A) By increasing server load B) By reducing page reloads and providing seamless updates C) By blocking user input D) By encrypting user data Answer: B Explanation: AJAX allows partial updates, reducing wait times and making the interface smoother. Question 24. Which of the following is NOT a purpose of AJAX? A) Real-time full-duplex communication B) Partial page updates C) Asynchronous server communication D) Enhancing interactivity Answer: A Explanation: AJAX is not meant for persistent, full-duplex communication like WebSockets. Question 25. In the context of AJAX, what does asynchronous mean? A) Requests are processed sequentially B) Requests do not block user interaction C) Requests are encrypted D) Requests always fail Answer: B Explanation: Asynchronous means requests happen in the background, without freezing the UI.
Question 29. What does the responseXML property of XMLHttpRequest provide? A) The response as a plain text B) The response as an XML Document object C) The HTTP status D) The request headers Answer: B Explanation: responseXML provides the server response parsed as XML. Question 30. Which aspect of AJAX helps prevent unnecessary data transmission? A) Using CSS B) Client-side caching C) Full page reload D) Server-side scripting Answer: B Explanation: Client-side caching reduces redundant requests and data transmission. Question 31. What is the main security risk associated with dynamically injecting content via AJAX? A) SQL Injection B) Cross-Site Scripting (XSS) C) Buffer overflow D) CSRF Answer: B Explanation: Injecting content without validation can expose the site to XSS attacks. Question 32. How does the Fetch API differ from XMLHttpRequest?
A) Fetch works only in old browsers B) Fetch uses Promises for asynchronous operations C) Fetch cannot send POST requests D) Fetch does not support JSON Answer: B Explanation: Fetch uses Promises, making asynchronous code cleaner and more manageable. Question 33. How do you handle errors in Fetch API requests? A) Using a catch block B) Using onerror event C) Using status property D) Using responseText Answer: A Explanation: Errors are caught using .catch() on the returned Promise. Question 34. What does Promise chaining allow in AJAX programming? A) Multiple AJAX requests run in parallel B) Sequential asynchronous operations C) Synchronous blocking D) Immediate response Answer: B Explanation: Promise chaining enables handling multiple asynchronous steps in sequence. Question 35. Which method is used to load HTML fragments via jQuery? A) $.get()
C) Better CSS handling D) Easier DOM manipulation Answer: B Explanation: WebSockets provide real-time, two-way communication, unlike AJAX. Question 39. Which property of XMLHttpRequest provides the HTTP status code? A) status B) responseText C) readyState D) onreadystatechange Answer: A Explanation: The status property returns the HTTP status code of the response. Question 40. What is the role of the async flag in the open() method? A) It sets the HTTP method B) It makes the request asynchronous C) It sets the request URL D) It determines the response format Answer: B Explanation: The async flag determines if the request runs asynchronously. Question 41. Which JavaScript function is used to create a new HTML element for DOM updates? A) createElement() B) appendChild() C) querySelector()
D) innerHTML() Answer: A Explanation: createElement() generates new HTML elements for dynamic content. Question 42. What does throttling an event handler achieve in AJAX applications? A) Increases server load B) Reduces the frequency of AJAX requests C) Disables the event handler D) Encrypts requests Answer: B Explanation: Throttling limits the rate of event-triggered AJAX requests. Question 43. Which jQuery method handles asynchronous form submissions? A) $.ajaxForm() B) $.submit() C) $.ajax() D) $.serialize() Answer: C Explanation: $.ajax() can be used to asynchronously submit form data. Question 44. What is the main purpose of the dataType option in jQuery's $.ajax()? A) To specify the target element B) To define expected response format C) To set request headers D) To determine HTTP status
Explanation: Graceful degradation ensures usability even if AJAX or JavaScript is unavailable. Question 48. What is the main reason to use HTTPS for AJAX requests? A) Faster loading B) Secure data transmission C) Larger data size D) Easier coding Answer: B Explanation: HTTPS encrypts data, protecting it during transmission. Question 49. How can you prevent Cross-Site Request Forgery (CSRF) in AJAX? A) Using GET requests only B) Including anti-CSRF tokens in requests C) Disabling cookies D) Using only HTTP Answer: B Explanation: Anti-CSRF tokens validate requests, preventing CSRF attacks. Question 50. Which event is triggered when a file upload completes using AJAX? A) onreadystatechange B) onload C) onprogress D) onerror Answer: B Explanation: onload fires when the file upload is complete.
Question 51. What does debouncing accomplish in AJAX-powered search boxes? A) Delays requests until typing stops B) Sends requests instantly C) Blocks all requests D) Ignores user input Answer: A Explanation: Debouncing waits for user input to pause before sending the request. Question 52. How do you update an existing DOM element’s text in JavaScript? A) innerHTML B) textContent C) value D) src Answer: B Explanation: textContent sets the text of an element, updating its content. Question 53. What is the main advantage of using JSON over XML in AJAX? A) JSON is more verbose B) JSON parses faster and is less complex C) JSON supports more tags D) JSON requires specific browsers Answer: B Explanation: JSON is lightweight and easier for JavaScript to parse.
A) Timeout and failed requests B) Only successful responses C) Ignoring errors D) Disabling loading indicators Answer: A Explanation: Handling timeouts/errors improves usability and informs users. Question 58. What is a common way to show a loading indicator during AJAX requests? A) Using alert() B) Updating CSS to show/hide elements C) Refreshing the page D) Disabling the submit button Answer: B Explanation: CSS classes or styles can be used to toggle loading indicators. Question 59. Which JavaScript method is used to remove a DOM element? A) removeElement() B) deleteNode() C) removeChild() D) remove() Answer: D Explanation: remove() deletes an element from the DOM. Question 60. How do you prevent the default form submission in JavaScript? A) event.preventDefault()
B) stopPropagation() C) cancelSubmit() D) disableForm() Answer: A Explanation: event.preventDefault() stops the browser's default form submission. Question 61. Which method in jQuery serializes form data for AJAX submission? A) $.serialize() B) $.formData() C) $.send() D) $.ajaxForm() Answer: A Explanation: .serialize() converts form fields to a query string format. Question 62. What does the .catch() method do in a JavaScript Promise? A) Executes when the Promise resolves B) Handles errors or rejected Promises C) Chains Promises D) Serializes data Answer: B Explanation: .catch() is used to handle errors in Promises. Question 63. Which object is used for file uploads in AJAX? A) FileUpload B) FormData
