JavaScript Tricky Interview Questions

JavaScript Tricky Interview Questions

Practice here the best JavaScript Tricky Interview Questions and Answers.

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Below are the list of Best JavaScript Tricky Interview Questions and Answers

Type coercion is the process of converting value from one type to another (such as string to number, object to boolean, and so on)

By using Number.isInteger() function

In JavaScript, Object Equality is used for two purposes basically. "==" is used for comparing two variables by ignoring its data type whereas "===" is used for comparing two variables by checking its data type.

"===" is used instead of "==" because it can compare two variables by checking data type.

typeof() is a unary operator that returns a string indicating the type of the unevaluated operand whereas instanceof() is a binary operator, accepting an object and a constructor that returns a boolean indicating whether or not the object has the given constructor in its prototype chain.

To delete an element from the javascript array you can use the following technique:

  • pop - Removes from the End of an Array.
  • shift - Removes from the beginning of an Array.
  • splice - removes from a specific Array index.
  • filter - allows you to programmatically remove elements from an Array.

You can create an object whose prototype is a given object by the given method i.e. var o = Object. create(Object); it creates a new blank object o whose prototype is the Object function.

To add a number to two variables at once with the help of the following example( foo += -bar + (bar += x)) where x is the number that is added to both variablLinting is the process of running a program that analyses your code for programmatic and stylistic errors.

The steps to get URL and and its parts in JavaScript are:

  • window.location.protocol = “http:”
  • = “”
  • window.location.pathname = “/example/index.html”
  • = “? s=flexbox”

str.trim() method is used to remove the white spaces from both the ends of the given string.



Return value: This method returns a new string, without any of the leading or the trailing white spaces.

You can use the following code to strip whitespaces from String in JavaScript:

<!DOCTYPE html> 





        How to remove spaces from 

        a string using JavaScript? 





    <h1 style="color: green"> 

        Online Interview Questions 




        How to remove spaces from 

        a string using JavaScript? 




        Original string is:  

        Online Interviews Questions 




        New String is:  

        <span class="output"></span> 



    <button onclick="removeSpaces()"> 

        Remove Spaces 



    <script type="text/javascript"> 

        function removeSpaces() { 

            originalText =  

                "Online Interviews Questions"; 


            newText =  

                originalText.replace(/ /g, ""); 



                    = newText; 







Strip Whitespaces