40+ OodlesTechnologies Interview Questions and Answers

The return type of getElementsByClassName method in JavaScript is an array of elements.

• The method returns an array of elements that have a specified class name.

• The elements are returned in the order they appear in the document.

• If no elements are found with the specified class name, an empty array is returned.

Javascript is single-threaded.

• Javascript runs on a single thread called the event loop.

• This means that it can only execute one task at a time.

• However, it can delegate tasks to other threads using web workers.

• This allows for parallel processing without blocking the main thread.

Implement a function to find the index of a given integer in a singly linked list.

• Traverse the linked list while keeping track of the index of each element.

• Compare each element with the target integer 'N'.

• Return the index if 'N' is found, otherwise return -1.

• Handle cases where the list is empty or 'N' is not found.

• Consider the constraints on the number of test cases and the length of the linked list.

JavaScript data types include string, number, boolean, object, function, undefined, and null.

• String: 'hello'

• Number: 42

• Boolean: true or false

• Object: { key: 'value' }

• Function: function() { }

• Undefined: undefined

• Null: null

Async/Await is a feature in JavaScript that allows for easier handling of asynchronous code.

• Async/Await is built on top of Promises and provides a more readable and concise way to work with asynchronous code.

• The 'async' keyword is used to define a function as asynchronous, allowing the use of 'await' inside it to pause execution until a Promise is settled.

• Using Async/Await can help avoid callback hell and make code more maintainable and easier to understand.

• Example: async fun...read more

typeof() operator in JavaScript is used to determine the data type of a variable or expression.

• typeof() returns a string indicating the type of the operand.

• Example: typeof 42 will return 'number'.

• Example: typeof 'hello' will return 'string'.

Data can be shared between components in Angular using services, input/output properties, and observables.

• Use services to create a shared data service that can be injected into multiple components

• Use input/output properties to pass data from parent to child components

• Use observables to create a data stream that can be subscribed to by multiple components

Types of data binding in Angular include interpolation, property binding, event binding, two-way binding.

• Interpolation: {{ data }}

• Property binding: [property]="data"

• Event binding: (event)="function()"

• Two-way binding: [(ngModel)]="data"

JavaScript is single-threaded.

• JavaScript is single-threaded, meaning it can only execute one piece of code at a time.

• This is because JavaScript runs in the browser's main thread, which is responsible for handling user interactions, rendering, and running JavaScript code.

• Asynchronous operations in JavaScript, such as AJAX requests and setTimeout, allow for non-blocking code execution without the need for multi-threading.

• Web Workers can be used to run JavaScript code in the bac...read more

Implement a Stack data structure using a Singly Linked List with operations in O(1) time.

• Create a class named Stack with getSize, isEmpty, push, pop, and getTop methods.

• Use a Singly Linked List to store the elements of the stack.

• Ensure each operation runs in constant time complexity (O(1)).

• Handle edge cases like empty stack appropriately.

• Example: For input '5', '3 10', '5', '1', '2', '4', the output should be '10', '1', 'false'.

Given a singly linked list of integers and a reference to a node, delete the specified node from the linked list.

• Traverse the linked list to find the node to be deleted

• Update the pointers to skip over the node to be deleted

• Print the modified linked list after deletion

Return the top view of a binary tree given in level-order format.

• Traverse the binary tree in level-order and keep track of the horizontal distance of each node from the root.

• Use a map to store the nodes at each horizontal distance, and only keep the first node encountered at each distance.

• Return the values of the nodes stored in the map in sorted order of their horizontal distance.

• Example: For the given binary tree, the top view will be {10, 4, 2, 1, 3, 6}.

Detect if a singly linked list has a cycle using O(N) time complexity and O(1) space complexity.

• Use Floyd's Tortoise and Hare algorithm to detect cycle in linked list

• Maintain two pointers, slow and fast, moving at different speeds

• If there is a cycle, the two pointers will eventually meet

• If one of the pointers reaches the end of the list (null), there is no cycle

Position relative is relative to its normal position, while position absolute is relative to its nearest positioned ancestor.

• Position relative moves an element relative to its normal position.

• Position absolute moves an element relative to its nearest positioned ancestor.

• Position absolute elements are taken out of the normal flow of the document.

Functional components are simpler and easier to test, while class components have more features and lifecycle methods.

• Functional components are written as JavaScript functions, while class components are written as ES6 classes.

• Functional components are stateless and do not have their own internal state, while class components can have state.

• Functional components do not have lifecycle methods, while class components have lifecycle methods like componentDidMount and componentDi...read more

The typeof() method in JavaScript returns the data type of a variable or expression.

• typeof() returns a string indicating the type of the operand.

• It can be used with variables, literals, or expressions.

• Common return values include 'number', 'string', 'boolean', 'object', 'function', and 'undefined'.

The states of a promise object are pending, fulfilled, or rejected.

• A promise starts in the pending state.

• When a promise is resolved, it transitions to the fulfilled state.

• If a promise encounters an error, it transitions to the rejected state.

• Once a promise is settled (fulfilled or rejected), it cannot transition to any other state.

z index determines the stacking order of elements on a webpage.

• z index is a CSS property that specifies the stack order of an element

• Elements with a higher z index value will be displayed on top of elements with a lower value

• Default z index value is 0, negative values are allowed

• z index only works on positioned elements (position: relative, absolute, fixed)

No, const does not make the value immutable.

• const only makes the variable itself immutable, not the value it holds.

• For objects and arrays, const prevents reassignment but allows mutation of properties or elements.

• To make a value truly immutable, you can use Object.freeze() or other techniques.

Async/await is a syntax for writing asynchronous code in a synchronous way.

• Async/await is built on top of Promises.

• Async functions always return a Promise.

• Await can only be used inside an async function.

• Async/await makes code easier to read and write compared to using callbacks or Promises.

A Python program in recursion

• Recursion is a technique where a function calls itself to solve a problem

• The function should have a base case to stop the recursion

• The function should have a recursive case to continue the recursion

• Example: Factorial of a number using recursion

• Example: Fibonacci series using recursion

To import views in Django, you need to create a views.py file and import it in urls.py

• Create a views.py file in your Django app directory

• Define your views in the views.py file

• Import your views in urls.py using the 'from . import views' syntax

• Map your views to URLs in urls.py using the 'path()' function

Custom Hooks are reusable functions in React that allow you to extract logic from components.

• Custom Hooks are functions that start with the word 'use' and can call other Hooks if needed.

• They are used to share stateful logic between components without using higher-order components or render props.

• Custom Hooks can be used to handle common tasks like fetching data, managing form state, or subscribing to events.

• They promote code reusability and make it easier to separate concerns...read more

Closures, promises, callbacks, and asynchronous programming are all important concepts in Node JS development.

• Closures are functions that have access to variables in their outer scope.

• Promises are objects that represent the eventual completion or failure of an asynchronous operation.

• Callbacks are functions that are passed as arguments to other functions and are executed when the other function completes.

• Asynchronous programming allows multiple tasks to be executed concurrentl...read more

useState() is a React hook that allows functional components to manage state.

• useState() is used to declare a state variable in a functional component.

• It returns an array with two elements: the current state value and a function to update the state.

• The initial state value is passed as an argument to useState().

• The state can be updated by calling the update function returned by useState().

• useState() can be used multiple times in a component to manage multiple state variables.

Models in Django are Python classes that define the structure of the database tables.

• Models are used to create, read, update and delete data from the database.

• They define the fields and their types, relationships between tables, and constraints.

• Models can be created using the Django ORM (Object-Relational Mapping) or by writing SQL.

• Example: class Book(models.Model): title = models.CharField(max_length=100) author = models.ForeignKey(Author, on_delete=models.CASCADE)

• Models are...read more

Props are read-only properties passed from a parent component to a child component in React.

• Props allow data to be passed down the component tree.

• Props are immutable and cannot be modified by the child component.

• Props can be used to customize the behavior or appearance of a component.

• Props are accessed using the dot notation, like this.props.propName.

• Props can be any type of data, including strings, numbers, objects, or functions.

Program to generate a particular series

• Define the series pattern

• Use loops to generate the series

• Store the series in an array

• Print the array

Job description outlines duties and responsibilities of a job, while job specification outlines qualifications and skills required for the job.

• Job description explains what the job entails, while job specification explains what qualifications and skills are needed to perform the job.

• Job description is a summary of the job, while job specification is a detailed list of qualifications and skills required for the job.

• Job description is used for recruitment and selection, while j...read more

Function to determine if a number is prime or not.

• Check if the number is less than 2, return False if so

• Iterate from 2 to the square root of the number, checking for divisibility

• If no divisors found, return True (number is prime)

Create a function to find the least repeating consecutive character in a string.

• Iterate through the string and keep track of consecutive characters and their counts

• Find the character with the least count of consecutive repetitions

• Return the character with the least count

Call by value passes a copy of the variable's value, while call by reference passes a reference to the variable's memory location.

• Call by value passes a copy of the variable's value, so changes made to the parameter inside the function do not affect the original variable.

• Call by reference passes a reference to the variable's memory location, so changes made to the parameter inside the function affect the original variable.

• In Python, all function arguments are passed by refere...read more

Intercepter and class are both used in JavaScript, but serve different purposes.

• Intercepter is used to intercept and modify HTTP requests and responses.

• Class is used to create objects with properties and methods.

• Intercepter is commonly used in frameworks like Angular and React.

• Class is a fundamental concept in object-oriented programming.

• Intercepter can be used to add authentication headers to requests.

• Class can be used to create multiple instances of an object with different...read more

Hoisting is a JavaScript behavior where variable and function declarations are moved to the top of their scope.

• Variable declarations are hoisted but not their initializations.

• Function declarations are fully hoisted.

• Hoisting can lead to unexpected behavior if not understood properly.

Maintain employee work by setting clear expectations, providing feedback, recognizing achievements, and offering growth opportunities.

• Set clear expectations and goals for each employee

• Provide regular feedback and coaching to help employees improve

• Recognize and reward achievements to motivate employees

• Offer growth opportunities such as training and development programs

• Create a positive work environment that fosters collaboration and teamwork

Asynchronous behavior in JavaScript can be achieved using callbacks, promises, and async/await.

• Callbacks: Functions passed as arguments to be executed once an asynchronous operation is completed.

• Promises: Objects representing the eventual completion or failure of an asynchronous operation.

• Async/Await: Syntactic sugar built on top of promises to write asynchronous code that looks synchronous.

Freelance bidding apps include Upwork, Freelancer, Fiverr, Guru, and PeoplePerHour.

• Create a strong profile showcasing your skills and experience

• Search for relevant projects and read the project description carefully

• Submit a competitive bid that highlights your qualifications and offers a fair price

• Communicate promptly and professionally with the client

• Deliver high-quality work on time and within budget

Yes, I am planning to pursue a Master's degree in Human Resource Management.

• I have already researched various universities and programs that align with my career goals.

• I plan to continue working while pursuing my degree part-time.

• I believe that further education will enhance my skills and knowledge in the field of HR.

• I am also interested in attending conferences and workshops to stay up-to-date with industry trends.

Reverse a string without using new variable

• Use two pointers, one at the beginning and one at the end of the string

• Swap the characters at the two pointers and move the pointers towards each other until they meet in the middle

SQL is a programming language used for managing and manipulating relational databases.

• SQL stands for Structured Query Language

• It is used to retrieve and manipulate data in relational databases

• Common SQL commands include SELECT, INSERT, UPDATE, DELETE

• Examples of SQL database systems include MySQL, PostgreSQL, Oracle

Recruitment process involves sourcing, screening, interviewing, and selecting candidates for a job.

• Identify job opening and create job description

• Source candidates through job portals, social media, referrals, etc.

• Screen resumes and shortlist candidates

• Conduct interviews and assessments

• Select the best candidate and make an offer

• Onboard the new hire

Remove duplicates from an array

• Use Set to remove duplicates

• Convert Set back to array

• Use filter() to remove duplicates

• Use indexOf() to check for duplicates