JavaScript also known as JS is a programming language that is one of the core technologies of the world wide web alongside HTML and CSS. Over 97% of websites use JavaScript on the client-side for Web Page behaviour often incorporating third-party libraries. All major web browsers have a dedicated JavaScript engine to execute the code on the user’s device.
Core Java plays an important role in any Java interview so here are some questions that will help in your interview.
Beginner Level Questions
Q. Mentions some key features of JavaScript.
It is quite lightweight i.e. large code does not put much load on the system. JavaScript is an open-source programming language, which means no licence is required to use it. It is an interpreted programming language. It can be easily used with Java and HTML. JavaScript is better for network-centric applications.
Q. Mention some key advantages of JavaScript.
Few key advantages of JavaScript are:
• This interaction with the server is very less.
• Its interfaces are very good.
• In this, the feedback reaches the visitors very quickly.
• Its interaction is very high.
Q. What are some disadvantages of JavaScript?
• JavaScript does not support multiprocessing.
• It does not have permission to write and read files.
• You cannot use multithreading in this.
• JavaScript does not support networking applications.
Q. Give a simple example of “Hello World” in JavaScript.
<script type=”text/javascript”>
document.write(“JavaScript Hello World!”);
</script>
Q. What’s the difference between JavaScript and JScript?
JavaScript computer language was created by the Netscape Company. But later Microsoft made a version of it and named it JScript to avoid any trademark problems. In other words, we can say that JScript and JavaScript are the same, the only difference is that JScript is made by Microsoft.
Q. What is the difference between Client-side JavaScript and Server-side JavaScript? The Client-side contains the basic language and all the predefined objects, which make it playable in any browser. Also, it can be directly embedded in the HTML page. And in this, the browser interprets this script at runtime.
Server-side contains relevant JavaScript, which runs on a server. And it can be deployed only after compilation.
Q. Which class is a superclass of all classes?
Java.lang. The object is the root class for all the Java classes and we don’t need to extend it. Every other Java class falls back under the object. All the different non-primitive types including arrays are inherited directly or indirectly from this class.
Advanced Level Questions
Q. What are the static keywords?
The static keywords are used with a class-level variable to make it global so that all the objects will be able to share the same variable. It can also be used with the method. A static method can use only static variables of the class and invoke only the static method of the class.
Q. What are finally and finalise in Java?
Finally is used with a try-catch block to put the code that you always want to execute even the execution is thrown by a try-catch block. Finally is just used for releasing the resources which were created by try block.
Finalise is a special method in object class that we can override in our classes. Finalize is called by the garbage collector to collect the garbage value when the object is getting it. This method is generally overridden to release the system resources when garbage value is collected from the object.
Q. What is type casting in Java?
Casting in Java is one of the top topics from which you can get questions in your interview. When we assign a value of one data type to a different data type then these two data types might not be compatible with each other, in the case of the conversion of int value to long then automatic conversion is done by Java and doesn’t require typecasting. But if data types are not compatible with each other then they need to be cast for conversion.
Q. What is an interface?
The interface is the core part of the Java programming language used a lot in JDK, Java design patterns, and most of the framework and tools. The interface provides a way to achieve abstraction in Java and use it to define the contract for the subclasses to implement.
The interface is a good starting point to define the type and create a top-level hierarchy in your code. In Java a class can implement multiple interfaces, it’s better to use the interface as a superclass in most cases.
Q. What is an Iterator?
The Iterator interface provides methods to iterate over any collection. We can get an Iterator instance from a collection using the Iterator() method. Iterator takes the place of enumeration in the Java collection framework. The Iterator allows the caller to remove the elements from the underline collection during the iteration. Java collection Iterator provides a generic way for the transversal elements of a collection and implements Iterator design patterns.
Q. What do you understand by thread priority?
Every thread when gets born is assigned with a priority value and usually higher priorities get precedence in execution but it also depends on the Thread Scheduler implementation which is OS-dependent. We can assign the priority of the thread but it doesn’t guarantee that higher priority will get executed before the lower-priority thread. Thread priority is an integer value that varies from 1 to 10 where one is the lowest and 10 is the highest priority thread.
Q. How to create a Daemon thread in Java?
Thread class setDaemon (true) is used for creating Daemon threads in Java. We used to call this method before calling the start() method else it will give an Illegal thread state exception.
Q. What happens when an exception is thrown by the method?
When an exception is thrown by the main() method, the Java runtime terminates the program and prints the exception message and stack trace in the console.
Q. How do you ensure that the N thread can access N resources without getting into a deadlock situation?
In the case when the N thread can access the N resources without getting into a deadlock situation, here is the key point in order. If we acquire resources in a particular order and release resources in reverse order then we can prevent the deadlock situation.
Parting Words
JavaScript is undoubtedly one of the high in-demand coding skills rightnow and will surely be in the future. This demand eventually increases the competitions for JavaScript jobs. Consequently, it has become essentially important for one to thoroughly prepare for the job interview.
I certainly hope that the questions discussed in this article will help you greatly in boosting your interview preparation. Also, if you are someone who is preparing for their interview on YouTube, I have got something for you. Why don’t you try LearnTube?
LearnTube is a YouTube plugin for students which can significantly boost your learning through YouTube. With LearnTube, you can give MCQs after each lesson and check on your learning. Moreover, the best part about learning with LearnTube is its curated way of teaching. LearnTube curates the top 1% content for you and provides them in the most structured way.
So, What’s stopping you now? Download LearnTube and boost your interview preparation!
