What is the primary purpose of WebSockets in web applications?
A. To enable real-time, bidirectional communication between the client and server
B. To handle form submissions
C. To perform server-side rendering
D. To manage user authentication
Answer: A
Which protocol does WebSocket use to establish a connection?
A. HTTP
B. FTP
C. SMTP
D. TCP
Answer: A
What is AJAX commonly used for in web development?
A. To perform asynchronous HTTP requests and update web content dynamically
B. To handle user authentication
C. To manage database connections
D. To perform server-side computations
Answer: A
How is a WebSocket connection established?
A. By sending an HTTP request with an Upgrade header to switch from HTTP to WebSocket
B. By performing a POST request to the server
C. By opening a standard TCP connection
D. By using a WebSocket URL in a script tag
Answer: A
What does AJAX stand for?
A. Asynchronous JavaScript and XML
B. Asynchronous JavaScript and XSLT
C. Asynchronous JSON and XML
D. Asynchronous JavaScript and XHTML
Answer: A
Which method is used in JavaScript to create a WebSocket connection?
A. new WebSocket(url)
B. new XMLHttpRequest(url)
C. createWebSocket(url)
D. connect(url)
Answer: A
What type of requests does AJAX use?
A. Asynchronous HTTP requests
B. Synchronous HTTP requests
C. WebSocket requests
D. FTP requests
Answer: A
How does WebSocket differ from HTTP in terms of communication?
A. WebSocket provides full-duplex communication, while HTTP is half-duplex
B. WebSocket is a protocol for handling file uploads, while HTTP is for data exchange
C. WebSocket uses a different port, while HTTP uses port 80
D. WebSocket is used for static content delivery, while HTTP is for dynamic content
Answer: A
What event is fired when a WebSocket connection is successfully established?
A. onopen
B. onmessage
C. onerror
D. onclose
Answer: A
Which method is used to send data over an established WebSocket connection?
A. send()
B. post()
C. request()
D. write()
Answer: A
How can you handle server responses in AJAX?
A. By defining a callback function for the onreadystatechange event
B. By using WebSocket onmessage event
C. By setting up a Promise
D. By using the send() method
Answer: A
What is the purpose of the XMLHttpRequest object in AJAX?
A. To create and manage asynchronous HTTP requests
B. To manage WebSocket connections
C. To handle form submissions
D. To render HTML content
Answer: A
Which status code indicates a successful WebSocket connection upgrade request?
A. 101
B. 200
C. 404
D. 500
Answer: A
What method is used to close a WebSocket connection?
A. close()
B. disconnect()
C. end()
D. terminate()
Answer: A
How does AJAX improve user experience on a web page?
A. By allowing asynchronous data updates without reloading the entire page
B. By providing static content
C. By handling server-side sessions
D. By managing database transactions
Answer: A
What does the onmessage event handler of a WebSocket do?
A. It processes incoming messages from the server
B. It initiates a new WebSocket connection
C. It handles connection errors
D. It closes the WebSocket connection
Answer: A
Which of the following is a common use case for WebSockets?
A. Real-time chat applications
B. Form validation
C. File uploads
D. Static content delivery
Answer: A
In AJAX, what is the purpose of the readyState property in the XMLHttpRequest object?
A. To indicate the current state of the request
B. To set the request method
C. To handle response data
D. To close the request
Answer: A
What does the status property of the XMLHttpRequest object represent?
A. The HTTP status code returned by the server
B. The state of the request
C. The size of the response data
D. The URL of the request
Answer: A
What is the maximum number of WebSocket connections a browser typically supports per domain?
A. 6
B. 10
C. 25
D. 100
Answer: A
Which method is used to check the status of an XMLHttpRequest object?
A. status property
B. check() method
C. response() method
D. readyState property
Answer: A
What is the onerror event handler of a WebSocket used for?
A. To handle errors that occur during communication
B. To initiate a WebSocket connection
C. To handle incoming messages
D. To close the WebSocket connection
Answer: A
How can AJAX be used to improve the performance of a web application?
A. By reducing the amount of data that needs to be reloaded from the server
B. By increasing the server’s response time
C. By improving server-side processing
D. By providing additional client-side storage
Answer: A
In WebSockets, what does the ping and pong mechanism do?
A. It helps to keep the connection alive and detect broken connections
B. It initiates a new connection
C. It handles data encryption
D. It processes incoming messages
Answer: A
How can you set up an AJAX request to handle JSON data?
A. By setting the Accept and Content-Type headers to application/json
B. By encoding data in XML format
C. By using WebSocket connections
D. By setting the dataType to text
Answer: A
What is the purpose of the abort() method in the XMLHttpRequest object?
A. To cancel an ongoing request
B. To initiate a new request
C. To handle response data
D. To set request headers
Answer: A
In AJAX, how can you send data to the server?
A. By using the send() method of the XMLHttpRequest object
B. By using the post() method of the WebSocket object
C. By setting up an FTP connection
D. By using the connect() method
Answer: A
What does the readyState value 4 indicate in an XMLHttpRequest object?
A. The request is complete and the response is ready
B. The request has been sent to the server
C. The connection has been opened
D. The request is being processed
Answer: A
How can you handle large data transfers using WebSockets?
A. By sending data in smaller chunks or messages
B. By using AJAX requests
C. By compressing data on the server
D. By using FTP for file transfers
Answer: A
What does the close() method of the WebSocket object do?
A. It closes the WebSocket connection
B. It sends a message to the server
C. It opens a new WebSocket connection
D. It checks the connection status
Answer: A
How can you update a web page dynamically using AJAX?
A. By modifying the DOM based on server responses
B. By reloading the entire page
C. By using server-side scripts
D. By using static content
Answer: A
What does the XMLHttpRequest setRequestHeader() method do?
A. It sets the value of an HTTP request header
B. It initializes the request
C. It sends the request to the server
D. It handles the server’s response
Answer: A
How can you handle cross-origin requests in AJAX?
A. By using CORS (Cross-Origin Resource Sharing) headers on the server
B. By modifying the request URL
C. By using WebSocket connections
D. By setting up a proxy server
Answer: A
What is a common use case for AJAX in modern web applications?
A. To asynchronously load new data without refreshing the page
B. To handle large file uploads
C. To perform server-side rendering
D. To manage user authentication
Answer: A
Which JavaScript event is triggered when a WebSocket connection is closed?
A. onclose
B. onopen
C. onmessage
D. onerror
Answer: A
What is the responseText property in XMLHttpRequest used for?
A. To get the response data as a string
B. To set the request headers
C. To send data to the server
D. To get the status code of the response
Answer: A
How can you handle binary data with WebSockets?
A. By setting the binaryType property of the WebSocket to blob or arraybuffer
B. By using JSON encoding
C. By compressing data
D. By using AJAX requests
Answer: A
In AJAX, what does the onreadystatechange event handler do?
A. It processes the changes in the readyState property of the XMLHttpRequest object
B. It opens a new request
C. It sends data to the server
D. It handles connection errors
Answer: A
How can you improve the scalability of WebSocket connections?
A. By using a WebSocket load balancer or server cluster
B. By limiting the number of connections
C. By reducing data payloads
D. By using separate WebSocket servers for each client
Answer: A
What does the responseJSON property in XMLHttpRequest provide?
A. The parsed JSON data from the server response
B. The raw response data as a string
C. The HTTP status code
D. The request headers
Answer: A
Which event is fired when an AJAX request encounters an error?
A. onerror
B. oncomplete
C. onmessage
D. onfail
Answer: A
How can you ensure data consistency in real-time applications using WebSockets?
A. By implementing message acknowledgment and retransmission mechanisms
B. By using AJAX polling
C. By limiting data updates
D. By using server-side data validation
Answer: A