Top 5 JavaScript Interview Challenges

JavaScript or JS is an extremely powerful and constantly evolving programming language. It facilitates the interaction of the utilizer with the web page. JavaScript helps in enhancing the exchanging power and appearance of a web page. Its other application is its usage in developing games and various applications.

An individual hoping to have a career in JavaScript must be prepared for a very challenging interview. Companies love to throw coding challenges and expect them to be solved in a board or a satisfactory platform. Many might complain about the coding task assigned during the interview, but there is no other way. Professionals need to showcase their talent and knowledge in the stipulated exam.

Thus, it is elementary to prepare oneself in dealing with the interview. Following questions might be of help to those aspirants aiming to master an interview in JavaScript.

1) It is of unmatched and unparalleled importance to understand the JS functions. Functions are the real essence of the scripting language and professionals are expected to have an in-depth understanding of the same. The unique feature of JS function is that it can be allocated to a variable passed as reasoning to other functions and can be conveniently returned from another. The surprising feature of JS is that if one marks a function as a variable, the variable name will be raised and it denies means of approach unless JS implementation confronts its definition. Call(), apply() and bind() are three things that a good JS developer knows in and out. These can be understood as the preliminary version of the device used to change operation to gain something. One needs to utilize bind() when there is a requirement for a function to be named later on, with a specific context. Call() or apply() finds its application when one wants to run the function promptly without any sort of alteration.

2) It is desired to have knowledge of JS scope and closure. The three major kinds of the scope of JS are global, local and block scope. The most used one is the global scope. When describing a variable locally, the local scope is utilized. Conditions and functions are regarded as blocks. Magical Scope can be obtained by applying a closure. JS closure is a function that is employed to return other functions and it envelops other data.

  • It is of utmost priority to understand works like object, function and global scopes. The global browser facilitates the functioning of the object. Changing of context and scope of program subsequently alters it.

3) It is very important to understand object well like Object.freeze() and Object.seal(). It accumulates Key, Value pairs. JS objects are capable of storing anything and everything, like another object, function, and list, as a value. It is advisable to have a grasp over Object.prototype(), Object.seal() and Object.freeze(). The first one provides many special functions with wide applications. The second one permits to configure but restricts addition or deletion of new properties. The third one fixes an object in order to avoid the modification of already existing properties.

4) Also, comprehending prototypical inheritance is of paramount importance. In customary JS, the concept of inheritance exists. It is accomplished using methods of prototyping. Things to remember in this ̶ class property and class methods are bound utilizing ‘this’ and ‘prototype’ objects respectively. Usage of ‘call()‘ function conveying ‘this‘ object is required to inherit property. Object.create() demands usage to their methods and to tie up prototypes of child and parent.

5) Next principle thing is to perceive callbacks and promises clearly. The functions executed after input/output operations are called callbacks. Unlike many, the JS provides callbacks to the asynchronous functions. Promises can be described as orderly wrappers for callbacks which facilitate personals to asynchronous codes.


  1. JavaScript | MDN
  2. JavaScript | Wikipedia

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Ayushi Gupta
As a content strategist, Ayushi specializes in writing on topics related to technology, business, and healthcare. She is passionate about writing about to advanced tools and technologies they need to know for succeeding in this competitive environment. She is writing this article on behalf of Sharda University. Read all published posts by Ayushi Gupta.