Sign in

There are some common interview questions.

Var vs Let vs Const —

var is a functional scoped variable and it’s re- declarable and re-assignable. if you assign a value without declaring the variable it should be var.

let is a block-scoped variable and it isn’t re- declarable but re-assignable. if you declare a variable with let in a block you can't access that variable outside the block.

const is also a block-scoped variable and it isn’t re- declarable and not re-assignable.

Null vs Undefined —

When we declare a variable and do not assign a value it is “undefined”. But when we declare a variable and want to keep blank but not “undefined” we use “null”.

Closure —

I am learning ReactJS for 6 months and every day I have learned some new things and I try to write something about what I learned today. Today I’m trying to talk about 10 basic things that every React developer needs to know.

1. React is a library

There is some difference between Framework and Library. React is a library, not a framework. You can make the whole website front-end and back-end and can work with databases also with the framework. but the library focuses only on one thing and React mainly focus only building a user interface.

2. JSX

The full form of JSX is JavaScript…

JavaScript is the most popular programming language. Every developer needs to know some common things to make programming easier.

Try to Catch and Throw Errors —

When a Javascript application run can occur much error. to avoid unexpected errors you can handle error with try and catch

try {
Block of code to try
catch(err) {
Block of code to handle errors

Spread Operator —

Spread Operator is takes in an iterable (array) and expands it to a list of arguments. The … spread operator is useful for many different tasks

JavaScript is one of the top most popular programming language for front-end web developers nowadays. For the popularity of javaScript in front-end development, Ryan Dahl develops another server-side runtime NodeJS for backend development. To simplify web development for the developers EcmaScript is adding many beautiful patterns to javaScript. Today I will try to discuss about the methods of the array in javaScript.


This is always returns the number of elements in the array.

const peoples = [“John”, “Kerry”, “Ana”];
peoples.length(); // Returns 3


Add a new items to the end of the array and returns index of new item.


Prodip Munshi

JavaScript Developer

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store