Ajax is an acronym for asynchronous JavaScript and XML. Contrary to popular belief, it is not a programming language but a combination of powerful technologies used to build asynchronous web applications on the client side. It also allows web pages to send and retrieve information to be displayed in an existing webpage.
This article will discuss some of the most common questions in Ajax interviews to give you the upper hand if you are looking for any AJAX-related job. Note that these will mostly be technical, and therefore, adequate technical preparation is crucial. Consider the following recommendations:
1. What Is AJAX?
AJAX is a set of technologies used in asynchronous web application development. It is not a programming language as most people believe. The term was coined from Asynchronous JavaScript and XML and therefore combined two browser functions that weren’t as popular despite existing for quite some time. This set of technologies supports interlay and the retrieval of asynchronous records through XMLHttpRequest and users XML and XSLT to record interchange and manipulation. The entire lot is bound by JavaScript, which is a programming language. AJAX also respects internet standards and can therefore work with a variety of browsers and networks worldwide.
2. What Are Some Of The Technologies That Make Up AJAX?
AJAX comprises several defined technologies that collectively function to enable the creation of asynchronous web applications. These include HTML and XHTML for data asynchronous records retrieval and presentation, respectively, CSS, which forms the presentation layer, JavaScript and a range of APIS that support asynchronous communications and JSON, XML or XSLT facilitating data exchange between the web server and client. All these technologies play important roles in creating dynamic web pages.
3. What Do You Mean By A Synchronous Request?
AJAX supports both synchronous and asynchronous requests. The synchronous request waits for the server to respond before proceeding with the script execution. The execution, therefore, stops until a response is communicated. It is the opposite of an asynchronous request where the process continues without a reply from the server, preferring to handle the reply after arrival. Remember, these two requests are normally used based on the request priority of a web service request. The careful configuration ensures that the server can respond to a user based on the provided commands.
4. Have You Used AJAX With Other Languages?
Yes. AJAX does not work independently, which may explain why it is popular among developers and software engineers. It works perfectly with JAVA, one of the most popular programming languages. Developers can easily use the Java Enterprise Edition to create related consumer pages and respond to incoming requests. JAVA can also join AJAX customers in corporate settings and conduct several server-aspect manipulations targeting AJAX customers.
5. What Do You Understand By An AJAX Event?
AJAX events are the different unique occasions or occurrences generated by AJAX requests. You are free to choose what to subscribe to based on your wants and preferences. There are two main events under this, namely local and global events. You can easily subscribe to the former inside the Ajax request object since they function as callback. However, global events are only triggered on the document for anyone listening.
6. Most People Confuse AJAX And JavaScript. Can You Tell The Differences?
Even though AJAX stands for Asynchronous JavaScript and XML, it is different from JavaScript. First, it is a set of technologies used in web development and not a programming language. In contrast, javascript is a programming language that developers use for client-side tasks when developing web applications. Lastly, AJAX forms part of JavaScript programming, while the latter is mainly used to control and manage a given webpage after download.
7. How Will You Advise Someone Interested In Improving Their AJAX Performance?
There are several ways to improve call performance in AJAX. One should first reduce the number of AJAX requests before carefully picking the event that triggers the AJAX request. Other hacks include using GET requests correctly, reducing the quantity of data relays and enhancing data security through caching. Your AJAX performance should improve drastically, allowing you to send and receive requests faster.
8. Mention Some Of The Common Features Of AJAX
AJAX has an array of features that make it unique. Users enjoy efficient and friendly features such as autocomplete suggestions during searches. This set of technologies helps in client-side template rendering, uses Observer pattern on JavaScript objects and arrays, helps bind live data and control data view, calls upon ANO.Net data services and contexts, and supports client component declarative instantiation. These features are important as they serve different functions, assuring clients a smooth time when developing web applications.
9. Can You Mention Some Of The Advantages Of AJAX.
AJAX offers an array of advantages in web development. First, it reduces bandwidth use when retrieving and storing data from a background database saving users from reloading the page. It also supports instant form validation, which gives it an edge over its counterparts. Other advantages include reduced latency-response time during request and response, which improves efficiency and asynchronous calls that can be made to the server saving a client from waiting for data before it is rendered. Lastly, AJAX has a highly functional and useful XMLHttpRequest object that helped in specific data transfer without the necessary page reload.
10. AJAX Also Has several Disadvantages. Mention Them.
AJAX is highly dependent on javascript and cannot function when the latter is disabled in the browser. It is a good option for websites but not web applications since it is complex, less secure and requires longer development durations. Users cannot also bookmark pages created in AJAX which generally has a slow response time since the page controls do not load simultaneously. Other limitations include the exposed functionality of view page display code, the inability of search engines to index AJAX developed pages and a limited XMLHttpRequest object which cannot retrieve information from different other servers.
11. You Have Repeatedly Mentioned XML HTTP Requests. Can You Explain More About Them?
XMLHttpRequest refers to APIs that manipulate and transfer XML data through the HTTP protocol connecting a client and server. It has various methods and properties that different scripting languages such as VBScript and JAvaScript use for this process. Some of the common formats used in data transfer are plain text, binary content, JSON and XML. This object helps clients access new information or update a webpage without necessarily reloading it. All the events that happen when a request is processed are recognized.
12. Mention The Different Methods Used In XML HTTP Request
There are six XMLHttpRequest methods that every AJAX user should be aware of. These include abort(), which cancels an ongoing request, send(content), which sends a request to the server and open(method, URL), which consists of several important parameters such as DELETE, HEAD, GET, POST and PUT used as methods. The URL part of this method refers to the request’s address. We also have the getAllRespinseHeaders(), which returns all the HTTP headers as a string and the setRequestHeader(label, value), which adds the label-value pair to the HTTP header.
13. Tell Us More About The Open() Method On AJAX
The Open() method in the XMLHttpRequest object is normally used when initializing a new or existing request. It users different request methods, optional attributes and URLs. These include open(method, URL), which contains POST, HEAD, DELETE, PUT and GET used to make RESTful requests. Open(method, URL, async) points out how the request should be handled after receipt by the server. A true value means that no response is needed before script execution, while a false value indicates that the script must get a response before moving to the next step.
14. How Would You Explain The AJAX Callback Function To A Colleague?
The AJAX callback Function is not as detailed as it sounds. It consists of several important steps that most people observe without even knowing. A client or internet user sends a request to the server, which is asynchronous and therefore excuses the user from waiting for a response. The server then receives the sent request as a message and processes the page for which the callback has been requested. It then relays this to the browser in the form of a JavaScript string code to be executed on the browser. It, therefore, defines the sending and response of requests.
15. How Does AJAX Work?
AJAX has a pretty easy working mechanism. It has an XMLHttpRequest object that communicates with the server, saving the user from unnecessary page reloads. This can be broken down into a number of steps. First, the user sends a request to the server from the browser prompting JavaScript to call the XMLHttpRequest object. The server then uses ASP.Net, PHP or JSP to interact with the database for data retrieval before relaying it to the XMLHttpRequest callback in XML to JSON. The browser will finally display this data in CSS or HTML without calling for a reload.
16. AJAX, Like Any Other Set of Technologies, Is Vulnerable To Security Threat. Can You Mention Some Of The Security Threats Related To The AJAX Code?
Several security threats exist whenever the AJAX code is used in the webpage. These include insecure access to the database since AJAX request calls exist in plain text formats, easier access and viewing of the data retrieved from the server as it is stored on the client browser and potential misuse of the whole AJAX code by hackers during cyber attacks as it can be easily seen through the vore page source. Monitoring of browsing sessions using scripts also poses a big security threat.
17. Mention The Most Common AJAX Frameworks
AJAX has several frameworks, given that it is a set of technologies. They are normally grouped based on their development languages. Examples are JavaScript frameworks such as Webix, Prototype, Dojo, AngularJS, Google Web Toolkit, MooTools, YIU Library and jQuery. Java Frameworks include ICEfaces, PrimeFaces, RichFaces, Java Server Faces and Apache Wallet. ASP.NET AJAX falls under the Windows .NET platform, Pyjs under Python and finally Ruby on Rails based on the Ruby framework.
18. What Would You Tell A Client Who Complaints Of His Inability To Use AJAX?
AJAX is a common website building technology that can work with different browsers. It is, therefore, quite popular among web developers, be it front or back-end developers. However, there are instances where it cannot be used. These include whenever one wants to show a page in a search engine, when the user intends to have a secure application and where the particular browser does not recognize or use JavaScript. Remember, AJAX goes hand in hand with JavaScript and, therefore, is impossible to access where JavaScript does not exist.
19. What Pushes Organizations And Developers To Use AJAX?
Most people and organizations use AJAX because of its advantages. However, it also has several basic goals that can easily align with users’ goals. These include: To reduce the network load, come up with and uphold an interactive user interface, offer a server and client-side framework, allow platform and AR Hite true neutrality and finally to support both asynchronous and synchronous communication. A user who wants to enjoy such functions will resort to using AJAX.
20. Have You Ever Experienced Any Usability Problems When Using AJAX?
Yes. AJAX has several usability problems that may make it challenging to use for non-programmers and beginners. First, it heavily influences the web page’s appearance during dynamic updates. It also modifies the state of the page owing to the dynamic changes, forcing a developer or user to define the page behaviour when it comes to navigation, bookmarks, sharing of URLs, page printing and back options. For navigation, a JavaScript framework can be used to define back and forward options and page refreshing.
21. What Do You Need to Cime Up With Your Own Ajax Functionality?
A developer should be knowledgeable in a number of aspects to come up with unique AJAX creations. Knowledge of Dynamic HTML and DHTML is necessary as it forms the basis of AJAX, allowing continuous interactions between users and browser pages. Remember DHTML consists of Document Object Model and CSS. One must also have a good grasp of JavaScript, an object-based language recognized by several browsers. Other essentials include the Document Object Model, or DOM, which handles structured documents and CSS, which allows the modification of sizes, colours, fonts and positions.
22. Can You Mention Renowned Applications That Use AJAX.
AJAX is pretty popular, which can be easily seen from the number of renowned applications using it. Out of all the popular websites and applications using this set of technologies, Twitter, Google Plus, YouTube, Instagram, Google Maps and Facebook are the most common. Remember, applications such as Twitter and Facebook allows you to get new information or feeds without reloading the pages, which also applies to YouTube. You don’t have to reload the whole page to play a new song or randomly access a video.
23. What Is The Best Return Type In AJAX? JavaScript, HTML, XML Or TEXT?
There is no particular recommended return type in AJAX. Your choice will depend on what you want to achieve or the surrounding situations. Even though most people prefer XML, given that it is represented in the acronym AJAX, you can use whatever you want. You can promptly free server-based or generated HTML fragments into a file or use an API to download or parse XML content from RESTful services. As for plain text, sever generated textual content if filed and relayed while JavaScrip allows you to create items at the client-side through its rival() feature.
24. When Are You Free To Start?
I recently cleared from my former workplace, so I am ready to start working here as soon as possible. Most of my things are in order, plus I live right across the block and would not, therefore, need some time to make arrangements for accommodation. I can therefore start coming to work as early as next week if this interview turns out successful. However, I am also highly flexible and will work with your timelines. I hope that you will communicate soon.
25. How Will You Deal With The Pressure That Comes With This Job?
I believe that the pressure associated with coding fuels me to be at my best. I have learnt that I work well under pressure and will easily put my best foot forward to succeed at this job if given a chance. However, I also prefer prior planning and will list what needs my attention at the start of the day, beginning with the most pressing ones first and working within the set deadlines. I am positive that I will easily handle the pressure of this job. I am also not shy to ask for help where necessary.
Conclusion
These 25 questions are frequently asked in AJAX interviews. Ensure that you prepare well in advance and research some of AJAX’s most challenging topics to increase your chances of landing a job. We wish you all the best.
