ES6 interview questions for experienced/ES6 Interview Questions and Answers for Freshers & Experienced

What is Generator function?

generator is a function which behaves like an iterator. It can stop, and resume from where it stopped earlier

Posted Date:- 2021-10-08 10:39:53

What is default parameters?

Default parameters are parameters which permit named parameters to start with default values if no value or undefined passes.

Posted Date:- 2021-10-08 10:39:31

what is meant by Class Expressions?

Class Expressions mean to define a class in ES6. Class expression are named and unnamed, both. It uses prototype-based inheritance.

Posted Date:- 2021-10-08 10:38:23

What is difference between CoffeeScript and es6 ?

Difference between CofeeScript and ES6:

Difference between CoffeeScript and ES6 is that CoffeeScript has all new features that ES6 has, and it compiles into JavaScript. But ES6 is a next level language, which uses compiler like Babel to convert code into ES5 (current version of JavaScript).

Posted Date:- 2021-10-08 10:36:56

What is difference between ES6 and typescript?

There is no exclusive difference between ES6 and Typescript. You can perform functions in ES6 which you can perform in Typescript. Only difference is that transcript can create ECMAScript only.

Posted Date:- 2021-10-08 10:36:35

Will ES6 Support Backend?

yes, ES6 will support Backend.

Posted Date:- 2021-10-08 10:36:18

What is Prototypal Inheritance in Javascript?

Inheritance alludes to a target's ability to retrieve methods and more different properties from an additional object. Targets can inherit attributes from a second object. Inheritance is present in JavaScript projects through an entity known as prototypes and hence this structure of inheritance is generally known as prototypal inheritance. Prototypal Inheritance aids in creating unique and admirable programming languages in JavaScript.

Thus, the key aim of Prototypal Inheritance makes an object point towards some other object and assume entirely its properties. This allows various specifications of a targeted object to allocate familiar properties.

Posted Date:- 2021-10-08 09:59:25

What is the use of let & const in JavaScript?

In modern javascript let & const are different ways of creating variables. Earlier in javascript, we use the var keyword for creating variables. let & const keyword is introduced in version ES6 with the vision of creating two different types of variables in javascript one is immutable and other is mutable.
const: It is used to create an immutable variable. Immutable variables are variables whose value is never changed in the complete life cycle of the program.
let: let is used to create a mutable variable. Mutable variables are normal variables like var that can be changed any number of time.

Posted Date:- 2021-10-08 09:58:12

How to create a Javascript class in ES6?

In Es6 you can create a class using the Class keyword.Below is sample javascript class in ES6.
class User{
constructor(name,age) { = name;
this.age = age;

getData() {
console.log( + " is " + this.age + " years old !");

var user = new User("foo", 7);

Posted Date:- 2021-10-08 09:57:52

Explain Destructuring Assignment in ES6?

Destructing assignment in another improvement in Es6. It allows us to extract data from array and objects into separate variables.


let full_name =['John','Deo'];

let [first_name,last_name]=full_name;

// outputs John Deo
Another example

let c=[100,200,330,400];

let [a,...b]=c;


// outputs 100 [200, 330, 400]

Posted Date:- 2021-10-08 09:57:37

List steps to install Babel?

Installation: In order to install Babel, you require node.js and NPM. Make sure Node.js is installed on your server.

To check node installed or not run below commands on your terminal.

node -v
npm -v
Installing Babel : We can install Babel CLI locally by running below command on terminal.

npm install --save-dev babel-cli

Posted Date:- 2021-10-08 09:57:11

What are the classes and proxies?

Class- You can use the patterns easily with OOP based class declaration. It works readily with constructors, supports base class access, inheritance and static methods. OOP refers to Object-Oriented Programming.

Proxies- With proxies, you get to create objects and you can host the objects with a huge behavior diversity. Proxies can help in profiling and logging as well.

Posted Date:- 2021-10-08 09:56:13

What is spread, default and rest parameter?

Spread Operator- Donated by ‘...’ and is followed by the variable. The syntax of the spread operator would look like this for example:- ‘...X’. Spread operators manipulated objects and arrays which is the prime reason it is used in ES6. It is used for copying the property of one object to another.

Default Operator- In order to initialize a function using default values, the default operator is deployed. The parameter’s value can be anything- a number or a function or null.

Rest Parameter- This operator is used for recovering all the arguments that are required to invoke a function. This allows us to put items belonging to different categories separate. The rest parameter allows combining the parameters in a common array parameter.

Posted Date:- 2021-10-08 09:55:54

Explain the reason for using ES6 classes.

ES6 classes have been found to be very useful to the developers. Some of the major uses of ES6 classes are as follows:

ES6 classes have a simpler and less error-prone syntax.
As far as setting up inheritance hierarchies are concerned, ES6 is considered as the best option as it uses new syntax with the old syntax which minimizes the errors and eases the process.
ES6 classes help in defending the developers from failing to use new ones properly with the constructor function. This is one of the most common errors that occur with the developers during the use of a new operator. Classes remove this error by having the constructor throw an exception if this proves to be an invalid object for the constructor.
Classes also help to call the method which is of the prototype’s version. This version is much simpler with the new ES6 syntax than the old versions.

Posted Date:- 2021-10-08 09:54:56

Destructuring Assignment

Destructuring assignment is a special syntax that allows you to "unpack" arrays or objects into a bunch of variables, as sometimes they are more convenient.

* Simple Destructuring
* Assign default value while destructuring
* Adding an Alias to a Destructured Assignment
* Adding an Alias to a Destructured Assignment

Posted Date:- 2021-10-08 09:54:08

Explain the motivation behind Symbols to ES6.

Symbols are a particular kind of object, newly added in the sixth version of ECMAScript which can be used as a unique property name in the objects. Using Symbol in the place of String (as it was done in the previous versions) allows the programmer to use different modules that can create properties that will not be problematic to each other. Another huge benefit of Symbols is that they can be made private and the properties defined cannot be accessed by any user or developer who does not have direct access to the Symbol. They comprise of a function that can be used to create different symbols that can work differently. But they do not have any literal syntax, unlike the other primitives of JavaScript.

Posted Date:- 2021-10-08 09:32:46

Explain Internationalization and Localization.

These are JavaScript standard APIs that assist with operations such as collation, number formatting, currency formatting, and date and time formatting.

1. Collation: It is a method for searching and sorting strings within a collection. It has a locale argument and is Unicode-aware.
2. Number Formatting: Localized separators and digit grouping can be used to format numbers. Style formatting, numeral system, percent, and precision are among the other items.
3. Currency formatting: Currency symbols, localized separators, and digit grouping are the most common ways to format numbers.
4. Date and time formatting: Localized separators and ordering are used for formatting. The format can be short or long, and other characteristics such as location and time zone can be included.

Posted Date:- 2021-10-08 09:28:07

What are the new String methods introduced in ES6?

There are four string methods introduced in ES6 that are listed as follows:


Posted Date:- 2021-10-08 09:27:17

What do you understand by the term Hoisting in JavaScript?

It is a JavaScript's default behavior, which is used to move all the declarations at the top of the scope before the execution of code. It can be applied to functions as well as on variables. It allows the JavaScript to use the component before its declaration. It does not apply to scripts that run in strict mode.

Posted Date:- 2021-10-08 09:26:57

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