ES6 Interview Questions with answers

Reliability Interview Questions

While answering in an interview, Communicate loudly and with a variety of tones to demonstrate your interest and enthusiasm. Take your time thinking about each question before responding so that you can provide a decent answer. Pay close attention to the questions and let the recruiter initiate the discussion. In this article, we will see the ES6 Interview Questions with answers.

ES6 interview questions

  1. In ES6, talk about the Destructuring Assignment.

Destructuring is a new feature in ECMAScript 2015 or ES6 that allows you to retrieve information from objects and arrays and store it in an independent variable. It allows us to recover smaller fragments from objects and arrays.

  1. How do you make a class in ES6?

This keyword is being used in the class’s creation. We can use class expressions or class declarations to include classes in the code. Functions and constructors are the only things that can be included in a class definition. These elements are referred to collectively as data members of the class.

Constructors in classes assign memory to the class’s objects. Functions in a class are in charge of executing commands on objects.

  1. What exactly do you mean by Generator function?

A generator introduces a new way of interacting with iterators and functions. The generator is a type of function which can be interrupted in the middle once or more than once and restarted later. A generator function is defined using the declaration function* function keyword followed by an asterisk.

When the generator is invoked, it does not execute its code. Rather, it returns a special object known as a Generator object, which is used to handle the execution.

  1. What is the default parameter?

To use the default parameters, we could even initialize called parameters with default values if no value or undefined is passed.

  1. What exactly do you imply by IIFE Instantly invoked function expressions?

IIFE is a JavaScript function that is called as soon as it is defined. The Self-Executing Anonymous Function is another name for it. It is divided into two major sections, which are as follows:

The first component is an anonymous function with lexical scope (static scope) that is encased in the Grouping operator ().

The second part generates the IIFE, which the JavaScript engine will use to immediately perceive the function.

  1. Talk about the for…of loop.

This loop is used to iterate through the iterables arrays, string, etc.

  1. Define the term set.

A set is a type of data structure that makes it possible to create a catalogue of distinct values. It is a set of values that is equivalent to arrays but does not contain any duplicate data. It accepts object references as well as primitive values.

  1. Define Map.

Prior to ES6, we would frequently use an object to map keys and values. Map objects are a new selection type introduced in ES6. It stores shared key values where any sort of value could be used as either a key or a value.

A map object remembers the order in which the keys were placed each time. Maps are ordered in such a way that they circumnavigate the elements in the order in which they were placed.

  1. What do you mean by “weak set”?

Weakly held objects can be stored in a collection using a weak set. Weak set, like set, cannot hold repeating groups. It is not possible to iterate on a weak set.

  1. What do you mean by “weak map”?

Weak maps are nearly identical to maps, except that the keys in weak maps have to be objects. It records every element as a key-value pair with weakly mentioned keys. Describe Promises in ES6.

Promises in ES6 are the most convenient way to get started with asynchronous programming in JavaScript. Asynchronous programming involves running processes independently from the original thread and notifying the main thread when they are finished.

Prior to ES6, asynchronous programming was accomplished through the use of Callbacks. Promises are being used to circumvent the issue of callback hell.

  1. In JavaScript, what do you mean by Callback and Callback hell?

Callback: It’s being used to manage the implementation of a function following the finalization of some other function’s execution. Collaborating with events would benefit from a callback. A function can be managed to pass as an argument to some other function in the callback. It is a fantastic strategy to cope with simple cases.

  1. Enumerate the distinctions between ES5 and ES6.

The essence of ES5 and ES6 is equivalent, however, there are some discrepancies. The following are the results of a comparison of ES5 and ES6:

Based on ES 5ES 6
DefinitionES5 is the fifth edition of the ECMAScript programming languageES6 is the sixth edition of the ECMAScript programming language Release
ReleaseIt was first released in 2009.It was first released in 2015.
Data-typesString, boolean, number, null, and unspecified primitive data types are supported by ES5.JavaScript data types have been enhanced in ES6.
Specifying VariablesWe could only define variables in ES5 by using the var keyword.Variables can now be defined in two new ways in ES6: let and const.
PerformanceBecause ES5 is older than ES6, it lacks some features, leading to lower effectiveness than ES6.Because of the additional features and the application of short-hand storage, ES6 outperforms ES5.
AssistanceIt has a broad range of communities.It has a sizable community following, but not as much as ES5.
ManipulationManipulation of Objects ES5 takes more time than ES6.Object manipulation in ES6 can be performed more smoothly thanks to destructuring and speed operators.
Arrow FunctionsTo define a function in ES5, the function and return keywords are both used.The arrow function is a major update launched in ES6 that eradicates the need to identify the function with the function keyword.
LoopsThe for loop is used in ES5 to iterate over elements.The for…of loop concept was introduced in ES6 to perform an iteration over the values of iterable objects.
  1. Modules are defined in JavaScript.

Modules are pieces of JavaScript code that are stored in a file. The use of Modules makes it simple to preserve, debug, and reuse code. When the programme is compiled, every module is a block of software that is accomplished.

  1. What exactly do you mean by “Hoisting” in JavaScript? 

JavaScript’s default mode is to place all declarations at the top of the purview before executable codes. It is applicable to both functions and variables.

  1. Define the term Babel.

Babel is a well-known JavaScript transpiler. It is primarily used to transform ES6 plus code into a backward-compatible edition of JavaScript that can be executed by past JavaScript engines.

  1. Webpack should be defined.

It is a JavaScript module bundler that accepts modules with interconnections. It enables us to run a Babel-hosted atmosphere.

  1. What exactly is ES6 or ECMAScript 2015?

ES6 was released in June 2015, and it is the language’s sixth edition. It was originally established as ES6 before being renamed ECMAScript 2015. Modules, iterators, classes, arrow functions, for…of loops, promises, and many other new features are included in this edition. Brendan Eich created it.

  1. Define the term ECMAScript.

The ECMA-262 standard defines the requirements for creating a general-purpose scripting language.

  1. What additional innovations are included in ES6?

The following are the unique additions introduced in ES6:

  • Keywords include let and const.
  • Default settings.
  • The arrow has a function.
  • Literals from a template
  • Object Literals are the literal translations of objects.
  • Operators for rest and spread.
  • Assignment for deconstruction.
  1. Define the keywords let and const.

let: Variables declared with the let keyword are malleable, which means their values can be altered. It is equivalent to the var keyword, but it allows for block scoping.

Const variables are unchanging and block-scoped when declared with the const keyword. When variables are declared with the const keyword, their values cannot be altered or relocated.

  1. What is the arrow function and how do you make one?

In ES6, arrow functions are initiated. Arrow functions are the abbreviation for ES6 functions. The arrow function definition shall consist of parameters, followed by an arrow (=>) and the function body.

The Arrow function is also known as the ‘fat arrow’ function. We can’t use them as builders.

  1. Can you provide an example of an Arrow function in ES6? Make a list of its benefits.

The following are the benefits of using the arrow function:

  • It reduces the size of the code.
  • For a single-line function, the return type is optional.
  • Connect the context lexically.
  • For a single-line statement, functional braces are not required.
  1. In ES6, what are template literals?

Template literals are a brand-new feature in ES6. It makes it simple to create multiline strings and undertake string interpolation.

Template literals, also known as string literals, enable ingrained expressions.

Template literals were known as template strings prior to ES6. The backtick ( ) character is used to surround template literals.

ES6 Interview Questions with answers

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