10 JavaScript Interview Questions for Advanced

It is always good to prepare before the interview and brush up on the fundamental ideas you have for the particular field. Here are ten advanced questions that would give you an edge during your interview.

Q1. State the difference between break and continue statements?

Ans. The essential difference between break and continue statements is that a break statement is used to come out of the loop. It continues executing the code after the loop if there is any available. However, a continue statement moves over one iteration of a loop and continues with the next iteration in the loop.

Q2. How can you insert another page in JavaScript by force?

Ans. To insert a page in JavaScript by force you have to use this code: -

<script language=”JavaScript” type=”text/javascript” >

<!--location.href=”http://newhost/newpath/newfile.html”; //--></script>

Q3. What are escape characters?

Ans. Sometimes using special characters like single quotes, double quotes, apostrophes, and ampersand, create misunderstandings for JavaScript. Thus, to resolve this, a backslash is used to turn special characters into string characters.

Example
document.write “she is a “smart” girl”
document.write “she is a \”smart\” girl”

Q4. What does pop()method do in JavaScript?

Ans. Unlike the Shift()method that operates at the beginning of the array, the pop()method takes the last element of the array and gives the caller back the value.

Example
Var vegetables = [“Raddish”,  “Tomato”, “Brinjal”];
Vegetables.pop() ;

Q5. Does JavaScript have a concept level scope?

Ans. The answer is no. JavaScript has a lone function-level scope and no block-level scope. The variable that is defined within the function has the scope only inside the function.

Q6. What are the main disadvantages of using innerHTML in JavaScript?

Ans. The main disadvantages of using the innerHTML in JavaScript are:

Content is replaced everywhere. When you decide to add, append, delete or modify the contents on a web page using innerHTML, all the content is replaced.
“appending to innerHTML” does not work.
By introducing valid and broken HTML in the document, we can break it since innerHTML does not give validation.
Using innerHTML turns out to be very slow. The contents are very slowly built, and the parsed contents and elements which are already done are reparsed, which costs time.

Q7. What is the use of the blur function?

Ans. When an element gets out of focus, a blur event is triggered. The blur() begins the blur event or attaches a function to run when such an event happens.

Q8. What is the meaning of variable typing?

Ans. Variable typing requires you to denote or assign a number to a variable and then assign a string to that variable itself. For example

x=9;
x=”Monica”;

Q9. Is it possible to find operating systems in client machines using JavaScript?

Ans. Yes. To do that you have to use ‘Navigator.appversion’ which will bring up the operating system in the client machine.

Q10. What kind of errors do you find in JavaScript?

Ans. There are three different types of errors to be found or come across while using JavaScript:

Load time errors or Syntax errors: These are also known as parsing errors. They occur while interpreting time in JavaScript.
Runtime errors: These are also called exceptions. They occur during executions after interpretation.
Logical errors: These occur when you don’t get the desired result after running the script because the logic implied is flawed.

Good luck with your interview!

Other useful articles: