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Preparing for an Amazon JavaScript interview can feel overwhelming, but with the right approach, you can succeed it. Amazon looks for the candidates who have a solid understanding of the JavaScript and can apply it to solve the real-world problems. In this blog, we’ll cover the essential JavaScript questions you might asked during your interview, along with the tips on how to approach them. Whether you’re new to coding or have the years of experience, this guide will help you to get ready and boost your confidence for the big day.
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Introduction
Amazon is a global leader in e-commerce, technology, and cloud computing, founded by Jeff Bezos in 1994. Starting as an online bookstore, it has expanded into the various sectors, including the Amazon Web Services (AWS), which powers much of the internet’s infrastructure, and the Amazon Prime, its popular streaming service. Amazon, one of the most significant businesses in the worlad, is well-known for its customer-centric business model and unwavering innovation.
One of the largest corporations in the world, Amazon expects to generate more than $780 billion in the revenue by 2024. It has transformed online shopping, logistics, and digital services and It is the world’s biggest internet store. A lot of people want to work with this global US technology company. Since the interviewers may evaluate your understanding of the company, it is important that you familiarize yourself with the Amazon before the interview.
Why Join in Amazon?
1. Creative Setting
With the advancements in the cloud computing, quantum computing, blockchain, and the artificial intelligence, Amazon is at the forefront of technological innovation and always pushing the envelope. One of the many opportunities available to the Javascript developers is the opportunity to work on the innovative projects that influence the direction of technology.
2. The Worldwide Effect
In this regard, the Amazon operates in more than 170 countries and offers services and solutions to a diverse variety of the industries. Here, working for Amazon will require being a member of an international team that tackles the pressing issues and provides the significant global answers. Additionally, a large audience will see and appreciate your work.
3. Professional Growth
Similar to the career development, Amazon is dedicated to its workers ongoing professional growth. Additionally, the organization provides a range of tools, certifications, and the training programs to assist you to develop your career and skill set. Additionally, the Amazon supports you during your career regardless of your preference to study new technologies or concentrate on a certain field.
4. A Culture of Collaboration
Amazon will promotes cooperation and a welcoming environment at work that stimulates creativity, innovation, and the teamwork. Additionally, you’ll have the chance to exchange ideas with some of the smartest individuals in the business and work together on the initiatives that actually will affect the change.
5. Great Pay and Benefits
Competitive pay and the first-rate benefits are offered by the Amazon. These consist of wellness initiatives, retirement plans, and the health insurance. Stock options and the bonuses are also provided by the corporation. At Amazon, the effort is well-rewarded. A healthy work-life balance is supported by these perks.
Amazon Interview Preparation Tips
1: Which of the following is a JavaScript framework/library?
In order to succeed in a Amazon Javascript interview, technical knowledge alone is not enough. Here’s tips to get you ready:
1. Recognize Your Position in the Organization
To understand the job completely, do some research on it. Take a close look at the description to grasp the primary responsibilities required. Compare your qualifications and experience to the job specifications. Determine the critical abilities required to succeed in this position. Make expectations clear by learning what qualities Amazon is looking for in applicants.
2. Enhance Technical Proficiency
Learn the fundamentals of Java first in order to scripts. Practice with Javascript, emphasizing tasks involving datatypes, methods and functions. Examine your Excel proficiency, particularly with object oriented programming (OOPs). To learn more, study common web developments and methods. To get experience, work on actual problems with datatypes and coding obstacles.
3. Get ready for questions on Experience.
To successfully structure your replies, use the STAR approach. Emphasize certain prior accomplishments that are unique to the position. Practice your answers to typical leadership and teamwork settings. When talking about what you’ve learnt from experiences, be sincere and thoughtful. Get stories and examples ready for common queries about behavior that you might run into.
4. Use mock interviews as practice
Engage in role-playing interviews with a friend or mentor to replicate authentic settings. Put on some clothes and approach the practice like it’s a true interview. To find out where you can make improvements in your comments, record yourself. To improve and make your responses more clear, ask for frank comments from others. Make an effort to be more succinct and clear in your responses.
5. Examine the Amazon Organisation
Recognize the background and path of Amazon’s success. Examine the market to find out who Amazon’s primary rivals are. Keep yourself informed about Amazon’s most recent initiatives and news. Get acquainted with the assortment of things that Amazon provides to its clientele. Find out what Amazon stands for and the company’s principles.
6. Get Ready with Your Questions
Inquire about the team’s structure and dynamics. Talk about the company’s training, professional development, and advancement opportunities. Recognize Amazon’s work culture, which includes the work-life balance. Make job obligations clear so that you are aware of the daily responsibilities involved. Demonstrate a will to overcome any obstacles the role may bring.
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Top Amazon Javascript Interview Questions and Answers
Q. Differences between JavaScript and Java?
Answer:
| JavaScript | Java |
| The JavaScript is an object-oriented scripting language. | The Java is an object-oriented programming language. |
| Applications written in JavaScript are designed to operate on a web browser. | Applications written in Java are typically designed to run on virtual machines and operating systems. |
| It is not necessary to compile JavaScript before executing the application code. | Before Java source code can be prepared for real-time execution, it must be compiled. |
Q. What kinds of data types are there in JavaScript?
Answer: Two forms of data exist in JavaScript: primitive and non-primitive data types.
- Primitive Data Types: A single value is stored in these data types. The Primitive data type’s sub-data types are listed below.
- Types of Boolean Data: It keeps both real and fake values.
Example1:
varx = 2;
vary = 4;
varz = 5;
(x == y) // returns false
(x == z) //returns true
- Null data Types: It will stores either empty or unknown.
Example2:
var a = null;
- Undefined data Types: Variables that are merely declared—not defined or initialized—are stored there.
Example3:
var x; // x is undefined
var y = undefined; // We can alternatively change the y variable’s value to undefined.
- Number Data Types: It keeps both floating-point and integer values.
Example4:
var a = 2;
var b = 3.2;
- String data Types: It will keep both characters and alphanumeric values.
Example5:
var str1 = ” Entri App “;
var str2 = ‘Entri App is Learning App’;
Q. Which are the main languages used in object-oriented programming?
Answer: Object-Oriented programming languages are those that employ and adhere to the OOPs, or object-oriented programming paradigm. Among the most popular languages for object-oriented programming are:
- Java
- C++
- Javascript
- Python
- PHP
Q. Difference between “ == “ and “ === “ operators.
var a = 4;
var b = "4";
(a == b) // returns true since a and b have the same value (a === b).
(a === b) // Since the type of an is "number" and the type of b is "string," the result is false.Q. Differences between the JavaScript keywords let and var.
Answer:
- The JavaScript programming language has utilised the ‘var’ keyword since its inception, while the ‘let’ keyword was introduced in 2015.
- “Var” is a keyword with a function scope. The variable declared with the var keyword can be accessed anywhere in the function, but a variable declared with the ‘let’ keyword can only be used in the block in which it is declared.
- Let and const are hoisted but not initialised in ECMAScript 2015. The variable is in a “temporal dead zone” from the beginning of the block until the declaration is processed, therefore referencing it in the block before the variable declaration causes a ReferenceError.
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Q. Define NaN property in JavaScript?
Answer: The “Not-a-Number” value is represented by the NaN attribute. It displays a number that is not allowed.kind of NaN will provide a number.
Q. Differences passed by value and passed by reference.
var a = 5;We made the variable an in the example above and gave it the value “5”. The assign operator, “=,” allocates memory in the background, stores the value “5”, and then returns the address of the memory space that has been allotted. Consequently, rather than directly linking to the value 5, the variable an in the code above points to the location of the memory space.
Q. What is strict mode in javascript and list out its characteristics?
- Developers do not allow duplicate parameters.
- You cannot use the JavaScript keyword as a function name or parameter when using strict mode.
- At the beginning of the script, strict mode is defined using the ‘use strict’ keyword. All browsers support the Strict mode.
- Global variables cannot be created by engineers in “Strict Mode.”
Q. What is Higher Order Functions in javascript?
Examples:
function higherOrder(fn) {
fn();
}
higherOrder(function() { console.log("Entri App") }); function higherOrder1() {
return function() {
return "Entri";
}
}
var a = higherOrder1();
a() // Returns "Entri"Q. Define “this” keyword.
function doSomething() {
console.log(this);
}
doSomething();Q. Differences between exec () and test () methods in javascript?
Answer:
- JavaScript uses the RegExp expression methods test() and exec ().
- To search a string for a specific pattern, we’ll use exec (). If the pattern is found, the function will return it straight; if not, it will return ’empty’.
- A test () will be used to locate a string for a particular pattern. When it locates the provided text, it will return the Boolean value “true”; otherwise, it will return “false.”
Q. What is currying in JavaScript?
function add (x) {
return function(y){
return x + y;
}
}
add(2)(5) Q. What is DOM?
Answer:
- The acronym for Document Object Model is DOM. A programming interface used for HTML and XML documents is called DOM.
- The browser builds an object known as DOM based on the HTML document when it attempts to render an HTML document. We can alter or modify different HTML document elements by using this DOM.
Q. Explain rest parameter and spread operator?
Answer:
- It offers a better method for managing a function’s parameters.
- We can write functions that can accept a variable number of arguments by using the rest parameter syntax.
- The remainder parameter will turn any number of inputs into an array.
- Additionally, it aids in extracting certain or all of the arguments.
- Three dots (…) can be placed before the parameters to use the rest of the parameters.
Spread operator (…):
The spread operator is used to spread an array and object literals, even though its syntax is precisely the same as that of the remainder parameter. When one or more parameters are anticipated in a function call, we also employ spread operators.
Q. Define the use of promises in javascript?
Answer: In JavaScript, asynchronous operations are managed by promises. Asynchronous activities were handled by callbacks prior to promises. However, employing many callbacks to handle asynchronous work can result in unmanageable code because of the limited capabilities of callbacks.There are four states for a promise object.
- Pending: A preliminary assurance. This condition indicates that the pledge is still pending and has not yet been accepted or rejected.
- Fulfilled: This state indicates that the async process has finished and that the promise has been met.
- Rejected: This state indicates that the async action failed because the promise was rejected for whatever reason.
- Settled: This indicates that the pledge has either been accepted or denied.
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Q. What is WeakSet in javascript?
- Weakset is made up entirely of objects.
- There is a weak reference to an object inside the weakset. This implies that an object within the weakset will be trash collected if it lacks a reference.
- WeakSet only provides three methods—add(), delete(), and has()—in contrast to Set’s nine.
const newSet = new Set([2, 4, 6, 8]);
console.log(newSet);// Outputs Set {2,4,6,8}
const newSet1 = new WeakSet([1, 2, 3]); //Throws an error
let obj1 = {message:"Entri App"};
const newSet2 = new WeakSet([obj1]);
console.log(newSet2.has(obj2)); // trueQ. Usage of callbacks?
Answer:
- A callback function is a method that is executed inside of another function (let’s call it “thisFunction”) after the function has finished running. It is supplied as an input to this other function.The programming language JavaScript is event-based.
- JavaScript won’t pause to wait for a response; instead, it will keep running and watch for more events. Callbacks are a way to make sure that a code doesn’t start until after another code has finished running.
Q. What is WeakMap in javascript?
- In a weakmap, an object should always be the keys and values.
- The item will be gathered as trash if there are no references to it.
const map0 = new Map();
map0.set('Value', 2);
const map1 = new WeakMap();
map1.set('Value', 3.4); // Throws an error
let obj = {name:"Alice"};
const map2 = new WeakMap();
map2.set(obj, {age:20});Q. Define Object Destructuring in Javascript?
- Object destructuring:
const classRoom = {
strength: 20,
benches: 33,
blackBoard:2 }
const classStrength = classRoom.strength;
const classBenches = classRoom.benches;
const classBlackBoard = classRoom.blackBoard;Q. Write down the differences between prototypal and classical inheritance?
Answer:
- In classic OO programming, programmers create objects, which are representations of real-time entities. The two categories of abstractions are classes and objects.
- An object is an abstraction of a real entity, while a class is a generalisation of an object. For instance, a vehicle is a car’s speciality. Cars (class) are hence descended from vehicles (object).
- In contrast to prototypal inheritance, which permits any object to be duplicated via an object linking technique, classical inheritance is limited to classes that inherit from those surviving classes. Not to get too technical, but a prototype basically acts as a model for those other objects, whether or not they extend the parent object.
Q. What is JavaScript Design Patterns?
- JavaScript Creational Design Pattern: This pattern addresses the object generation mechanism. Their goal is to create objects that fit into a specific situation.
- JavaScript Structural Design Pattern: This pattern describes how to build larger frameworks by combining the classes and objects we have produced thus far. This pattern defines a simple method for establishing relationships between things, which facilitates the process.
- Behavioural Design Pattern: This design pattern illustrates common JavaScript communication patterns between objects. The communication can proceed with more flexibility as a result.
Q. Which language is JavaScript—pass-by-value or pass-by-reference?
Answer: Because the data in the variable is always a reference to objects, it is always pass by value. Consequently, if you supply an object and modify any of its members within the method, the modifications persist outside of it.
In this instance, it seems to be pass by reference. It is clear that it is supplied by value since if you change the values of the object variable, the change will not be retained.
Q. Variations in how generators and async/await are used to accomplish the same task.
Answer:
- Async-await functions are executed sequentially, one after the other, whereas generator functions are run by their generator yield by yield, or one output at a time.
- A specific use case for Generators is made easier to implement by async/await.
- The Generator function consistently yields the value X and the done result is Boolean; nevertheless, the Async function consistently returns an error or an assurance.
Q. Define the primitive data types in JavaScript?
- Boolean
- Undefined
- Null
- Number
- String
Q. Explain the role of deferred scripts in JavaScript?
Q. What kinds of data types are there in JavaScript?
Answer: The various kinds of data that JavaScript can handle are as follows:
- Boolean: For values that are true or false
- Null: For values that are empty or unclear
- Undefined: Refers to variables that are merely declared without being initialised or defined.
- Number: For floating-point and integer values
- String: Used for alphanumeric and character values
- Object: For sets or intricate values
- Symbols: For distinct object IDs
Q. What characteristics does JavaScript have?
Answer: The attributes of JavaScript are as follows:
- Interpretive programming language that is lightweight
- Compatible with multiple platforms
- Source-free Object-oriented
- Combining several front-end and back-end technologies
- Specifically utilised in the creation of network-based applications
Q. In JavaScript, how do you build an object?
Answer: JavaScript supports and promotes the use of objects while creating web applications since it is fundamentally an object-oriented programming language.
const student = {
name: ‘Alice’,
age: 22
}
Q. In JavaScript, how do you build an array?
Answer: Here’s a very basic JavaScript array creation method that makes use of the array literal:
var X = [];
var Y = [‘1’, ‘2’, ‘3’, ‘4’, ‘5’];
Q. Which are some of the JavaScript built-in methods?
Answer:
| Built-in Methods | Keyvalues |
| Date() | It returns the present date and time |
| concat() | It will joins two strings and returns the new string |
| push() | It adds an item to an array |
| pop() | It will removes and also returns the last element of an array |
| round() | The rounds of the value to the nearest integer and then returns it |
| length() | This will returns the length of a string |
Q. In JavaScript, what are the scopes of a variable?
Answer: A variable’s scope indicates the locations of its declarations and definitions within a JavaScript programme. A variable can have one of two scopes:
Global Scope: In a JavaScript code, global variables with global scope are accessible anywhere.
Local Scope: Local variables can only be accessed from within the function that defines them.
Q. What is object prototypes?
- The Date prototype’s properties are inherited by Date objects.
- Properties of the Math prototype are inherited by Math objects.
- The Array prototype’s properties are passed down to array objects.
- Object.prototype sits at the top of the chain.All prototypes receive their methods and properties from the Object.prototype.
- An object’s blueprint is called a prototype. Even if the properties and methods are absent from the current object, we may still utilise the prototype to apply properties and methods to an object.
Q. What knowledge do you have regarding JavaScript?
Answer: JavaScript is a widely used web scripting language that can be used for both server-side and client-side development. JavaScript code is compatible with object-oriented programming and can be added to HTML pages that web browsers can comprehend and run.
Q. Explain the types of errors in javascript?
- Syntax errors: Syntax errors are typos or spelling issues in the code that result in the programme not starting at all or stopping midway through. Typically, error messages are also provided.
- Logical error: When the grammar is correct but the logic or programme is flawed, reasoning errors take place. In this instance, the application runs without any issues. The output findings, however, are unreliable. Since many programmes do not indicate errors for logic errors, these can occasionally be harder to fix than syntactic problems.
