Introduction to AJAX Interview Questions and Answers
AJAX is called as “Asynchronous JavaScript and XML” is a set of web techniques or standards used by the most of web technologies in the area of web pages development for rich user experience and less server loading for the content to be displayed. The data interchange format can be either XML or JSON where JavaScript is native to JSON (JavaScript Object Notation), most of the modern web applications use JSON as the data format to interact with the database servers. AJAX is not confined to a single technology and it consists of a group of technologies and can also be used with HTML, CSS, JavaScript and different JS libraries. The main of AJAX is to communicate with the server in the background with interrupting or reloading the existing web page by providing rich user experience to the client or end-user of the application.
Below is the list of AJAX Interview Questions and Answers:
So you have finally found your dream job in AJAX but are wondering how to crack the AJAX Interview and what could be the probable AJAX Interview Questions. Every interview is different and the scope of a job is different too. Keeping this in mind we have designed the most common AJAX Interview Questions and Answers to help you get success in your interview. The list is divided into two parts are as follows:
Part 1 – AJAX Interview Questions (Basic)
This first part covers basic interview questions and answers
1. What is AJAX and explain about it?
Answer:
AJAX (Asynchronous JavaScript and XML) is a group of technologies used to load the page content in the background without disturbing or changing the existing state of the web page. DOM (Document Object Model) API (Application Programming Interface) in the browser tree can be manipulated to provide the dynamic functionalities or to change the content of the web page dynamically. Asynchronous communication is another great feature of the AJAX and that can be achieved by using XMLHTTPRequest object which is an API present in the form of an object which a standard is given by WHATWG (Web Hypertext Application Technology Working Group) and was later moved to W3C (World Wide Web Consortium).
2. What are the different technologies used in AJAX?
Answer:
AJAX involves with different technologies such as HTML (and XHTML), CSS (for presentation layer), JSON, XML or XSLT (for data exchange between a web server and client), JavaScript and other APIs for asynchronous communication. AJAX is used for creating dynamic web pages. The examples of the websites those used AJAX are Google, Gmail, YouTube, Facebook etc. AJAX is a standard based on Internet Standards to comply with all the browsers and networks across the globe.
Let us move to the next AJAX interview question.
3. What is a synchronous request in AJAX?
Answer:
The synchronous and Asynchronous type requests in AJAX are used based on the request priority of the web server request and should be carefully configured to make the server respond to the user based on the user requirement. The synchronous request waits for the server’s response after making a request to proceed with next part of the script execution which is crucial in fast response mechanism and this should be avoided frequent times to make server high responsive. Wherever the synchronous request mechanism is essential or inevitable, there should it be used.
4. What is asynchronous request in AJAX?
Answer:
An Asynchronous request is defined as the script execution which allows proceeding with the next line of execution irrespective of the response from the web server after a request, which can be handled later upon the receipt of the response from web server. The asynchronous is the most import mechanism in providing the responses to the user without any delay where a user can still interact with the web pages irrespective of the responses from the server for the previous requests.
5. What are different ready states in AJAX?
Answer:
A ready state is a property present in the XMLHttpRequest object which holds the status of the XMLHTTPRequest. The different types of the status changes are available from 0 to 4 which are defined as 0 (Request not initialized), 1 (Established connection with Server), 2 (Request Received), 3 (Processing request) 4 (Request finished and a response is ready). When the status is 4, then the status can be described as HTTP status 200 (OK) which means the request is success and response is ready.
Part 2 – AJAX Interview Questions (Advanced)
Let us now have a look at the advanced Interview Questions.
6. What are the different stages and processes in AJAX ready states?
Answer:
The different states and its processes are initialization, requesting, processing and finished in AJAX. When an open method is called on an object, then the status changes to 1. When a send method is called then status changes to 2. After receiving the response from the server, when a request ends, the status changes to 4.
7. What is XMLHTTPRequest Object?
Answer:
XMLHTTPRequest (XHR) is a browser level API (Application Programming Interface) which processes the server-client requests using JavaScript. The XMLHTTPRequest object is present in the form of API to establish communication between a server and the browser client. XMLHTTPRequest is used to update the page content without reloading, request and receive data responses from the server even after completely loading the page, request and receive the responses from the server in the background without any interruptions to the user.
Let us move to the next AJAX Interview Questions.
8. What are the uses of XMLHTTPRequest Object in AJAX?
Answer:
An XMLHTTPRequest can be sent based on the ready state change status. An XMLHTTPRequest object can be created by calling constructor new XMLHTTPRequest( ). XMLHTTPRequest handles the Cross-Origin Resource Sharing (CORS). The garbage collection must not be done in XMLHTTPRequest object if the state is either an open state or in load, timeout, abort, error, loadend, readystatechange, and progress. There are different types of event handlers as well as supported in XMLHTTPRequest.
9. What are AJAX applications in web development?
Answer:
The different applications of the AJAX technologies include asynchronous calling, user-friendly, high-speed accessibility etc. The real-time applications or websites currently using the AJAX are Google, Gmail, Google Maps, Amazon Inc. etc., where the content to the users is displayed without reloading the entire web page. The other applications include data validation which happens instantaneously, validating the forms on a web page before submitting, autocompletion of data in the fields based on the initially typed words, refreshing dynamic data such as cricket scores, time, weather, loading of ads, stocks etc.
Let us move to the next AJAX Interview Questions.
10. What are the real-time AJAX web applications?
Answer:
The different types of real-time applications include security authentications which can be applied for the AJAX web applications on the server side and client side as well. XML in AJAX is least used whereas the JSON is the most used data format for the exchange of information across different sources. AJAX also provides the feature of fetching resources using Fetch API of XMLHTTPRequest object.
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This is a guide to AJAX Interview Questions with Answers. Here we have covered few commonly asked AJAX interview questions with their detailed answers so that it helps candidates to crack interviews with ease. You may also look at the following articles to learn more –
