Javascript Interview Questions and Answers, Javascript Interview Questions and Answers Freshers, Javascript Interview Questions and Answers, Javascript Interview Questions

Before getting on to the Javascript interview questions, the student must know that the Javascript is a continuously varying field which needs the students as well as professionals to upgrade their skills with the new features and knowledge, to get fit for the jobs associated with Javascript. This post related to Javascript Interview Questions and Answers, Javascript Interview Questions and Answers Freshers, Javascript Interview Questions and Answers, Javascript Interview Questions will help you let out find all the solutions that are frequently asked in you upcoming Javascript interview.

Over thousands of vacancies available for the Javascript developers, experts must be acquaintance with all the component of Javascript technologies. This is necessary for the students in order to have in-depth knowledge of the subject so that they can have best employment opportunities in the future. Knowing every little detail about Javascript is the best approach to solve the problems linked with problem.

APTRON has spent hours and hours in researching about the Javascript Interview Questions and Answers, Javascript Interview Questions and Answers Freshers, Javascript Interview Questions and Answers, Javascript Interview Questions that you might encounter in your upcoming interview.  All these questions will alone help you to crack the interview and make you the best among all your competitors.

First of all, let us tell you about how the Javascript technology is evolving in today’s world and how demanding it is in the upcoming years. In fact, according to one study, most of the companies and businesses have moved to the Javascript. Now, you cannot predict how huge the future is going to be for the people experienced in the related technologies.

Hence, if you are looking for boosting up your profile and securing your future, Javascript will help you in reaching the zenith of your career. Apart from this, you would also have a lot of opportunities as a fresher.

These questions alone are omnipotent. Read and re-read the questions and their solutions to get accustomed to what you will be asked in the interview. These Javascript interview questions and answers will also help you on your way to mastering the skills and will take you to the giant world where worldwide and local businesses, huge or medium, are picking up the best and quality Javascript professionals.

This ultimate list of best Javascript interview questions will ride you through the quick knowledge of the subject and topics like Array of Objects, Ordernow Function, Circumference Calculator Application. This Javascript interview questions and answers can be your next gateway to your next job as a Javascript expert.

These are very Basic Javascript Interview Questions and Answers for freshers and experienced both.

Q1: What is JavaScript?
A1: JavaScript is a client-side as well as server side scripting language that can be inserted into HTML pages and is understood by web browsers. JavaScript is also an Object based Programming language

Q2: What are JavaScript Data Types?
A2: Following are the JavaScript Data types:

  • Number
  • String
  • Boolean
  • Function
  • Object
  • Undefined

Q3: What is negative infinity?
A3: Negative Infinity is a number in JavaScript which can be derived by dividing negative number by zero.

Q4: What is ‘this’ keyword in JavaScript?
A4: ‘This’ keyword refers to the object from where it was called.

Q5: What is === operator?
A5: === is called as strict equality operator which returns true when the two operands are having the same value without any type conversion.

Q6: What are all the looping structures in JavaScript?
A6: Following are looping structures in Javascript:

  • For
  • While
  • do-while loops

Q7: What is the difference between JavaScript and jscript?
A7: Netscape provided the JavaScript language. Microsoft changed the name and called it JScript to avoid the trademark issue.In other words, you can say JScript is same as JavaScript, but it is provided by Microsoft.

Q8: Is JavaScript case sensitive language?
A8: Yes.

Q9: What is the use of window object?
A9: The window object is automatically created by the browser that represents a window of a browser.

It is used to display the popup dialog box such as alert dialog box, confirm dialog box, input dialog box etc.

Q10: How to write comment in JavaScript?
A10: There are two types of comments in JavaScript.

  1. Single Line Comment: It is represented by // (double forward slash)
  2. Multi Line Comment: It is represented by slash with asterisk symbol as /* write comment here */

Q11: What are the JavaScript data types?
A11: There are two types of data types in JavaScript:

  1. Primitive Data Types
  2. Non-primitive Data Types

Q12: How to create array in JavaScript?
A12: There are 3 ways to create array in JavaScript.

  1. By array literal
  2. By creating instance of Array
  3. By using an Array constructor

Let’s see a simple code to create array using object literal.
var emp=[“Shyam”,”Vimal”,”Ratan”];

Q13: Difference between Client side JavaScript and Server side JavaScript?
A13: Client side JavaScript comprises the basic language and predefined objects which are relevant to running java script in a browser. The client side JavaScript is embedded directly by in the HTML pages. This script is interpreted by the browser at run time.
Server side JavaScript also resembles like client side java script. It has relevant java script which is to run in a server. The server side JavaScript are deployed only after compilation.

Q14: What Is An Asynchronous Programming? Why Is It Important In JavaScript?
A14: In Asynchronous programming, the engine runs in an event loop. On encountering a blocking operation, a request gets fired and the code keeps running without blocking for the result. When its execution completes, and the response is ready, it fires an interrupt, which causes an event handler to be run, where the control flow continues. In this way, a single program thread can handle many concurrent operations in an asynchronous programming.

The user interface is asynchronous by nature and spends most of the time, waiting for user input to interrupt the event loop and trigger event handlers. Node is asynchronous by default. It means that the server works by waiting for a network request in a loop. Thus, it accepts more incoming requests, while the first one is getting handled.

It is important in JavaScript because it’s suitable for user interface code and beneficial for maintaining the performance on the server.

Q15: What Are The Different Ways To Create An Array In JavaScript?
A15: There are two main ways to create an array in JavaScript

Q16: What Is The Naming Conventions For The Variables In JavaScript?
A16: We have to follow the below rules while naming the variables in JavaScript.

  • Do not use any of the JavaScript reserved keywords as a name for your variable. For example, “break” or “boolean” are JavaScript keywords, and if used as variable names, it’s invalid.
  • JavaScript variable names should not start with a numeral (0-9). It must begin with a letter or the underscore character. For example, 123var is an invalid variable name, but _123var is a valid one.
  • Also, JavaScript variable names are case sensitive. For example, test and Test are two different variables.

Q17: How To Delete A Cookie Using JavaScript?
A17: To delete a Cookie, we have to set its expiry date to a time that occurred in the past. If attempts are made to read a deleted Cookie then, nothing is returned.

Q18: What is callback?
A18: A callback is a plain JavaScript function passed to some method as an argument or option. Some callbacks are just events, called to give the user a chance to react when a certain state is triggered.

Q19: What is closure?
A19: Closures are created whenever a variable that is defined outside the current scope is accessed from within some inner scope.

Q20: Which built-in method sorts the elements of an array?
A20: sort() method sorts the elements of an array.

Q21: Which built-in method returns the characters in a string beginning at the specified location?
A21: substr() method returns the characters in a string beginning at the specified location through the specified number of characters.

Q22: How to read a Cookie using JavaScript?
A22: Reading a cookie is just as simple as writing one, because the value of the document.cookie object is the cookie. So you can use this string whenever you want to access the cookie.

The document.cookie string will keep a list of name = value pairs separated by semicolons, where name is the name of a cookie and value is its string value.

You can use strings’ split() function to break the string into key and values.

Q23: What is a prompt box?
A23: A prompt box is a box which allows the user to enter input by providing a text box. Label and box will be provided to enter the text or number.

Q24: What do mean by NULL in Javascript?
A24: The NULL value is used to represent no value or no object. It implies no object or null string, no valid boolean value, no number and no array object.

Q25: How are JavaScript and ECMA Script related?
A25: ECMA Script is like rules and guideline while Javascript is a scripting language used for web development.

Javascript Conclusion Interview FAQs

We know the list of Javascript Interview Questions and Answers, Javascript Interview Questions and Answers Freshers, Javascript Interview Questions and Answers, Javascript Interview Questions is overwhelming but the advantages of reading all the questions will maximize your potential and help you crack the interview. The surprising fact is that this Javascript interview questions and answers post covers all the basic of the Javascript technology and you have to check out the FAQs of different components of Javascript too.

However, you will be asked with the questions in the interview related to the above mentioned questions. Preparing and understanding all the concept of Javascript technology will help you strengthen the other little information around the topic.

After preparing these interview questions, we recommend you to go for a mock interview before facing the real one. You can take the help of your friend or a Javascript expert to find the loop holes in your skills and knowledge. Moreover, this will also allow you in practicing and improving the communication skill which plays a vital role in getting placed and grabbing high salaries.

Remember, in the interview, the company or the business or you can say the examiner often checks your basic knowledge of the subject. If your basics is covered and strengthened, you can have the job of your dream. The industry experts understand that if the foundation of the student is already made up, it is easy for the company to educate the employ towards advance skills. If there are no basics, there is no meaning of having learnt the subject.

Therefore, it’s never too late to edge all the basics of any technology. If you think that you’ve not acquired the enough skills, you can join our upcoming batch of Javascript Training in Noida. We are one of the best institute for Javascript in noida which provide advance learning in the field of Javascript Course. We’ve highly qualified professionals working with us and promise top quality education to the students.

We hope that you enjoyed reading Javascript Interview Questions and Answers, Javascript Interview Questions and Answers Freshers, Javascript Interview Questions and Answers, Javascript Interview Questions and all the FAQs associated with the interview. Do not forget to revise all the Javascript interview questions and answers before going for the Javascript interview. In addition to this, if you’ve any doubt or query associated with Javascript, you can contact us anytime. We will be happy to help you out at our earliest convenience. At last, we wish you all the best for your upcoming interview on Javascript Technology.