JavaScript Assessment - Semi-Senior Level

JavaScript Assessment

Evaluate your development skills

Semi-Senior Level

20 Questions

🎯 Adaptive

70% To Pass

JavaScript ES6+ Node.js RESTful APIs Async/Await Promises

JavaScript Test

JavaScript Test - Semi-Senior Level

Test Semi-Senior Level

Question 1 of 3

What is the difference between var, let and const in JavaScript?

var has block scope, while let and const have global scope.
var allows variable redeclaration, but let and const do not.
let and const do not allow value assignment, but var does.
const allows changing the variable value, but let and var do not.

What is the concept of "hoisting" in JavaScript?

It is the ability to move functions to the top of the file.
It is the behavior by which variable and function declarations are moved to the beginning of their scope during compilation.
It is the ability to create objects with limited scope.
It is the ability to make code cleaner and easier to read.

What is a Promise in JavaScript?

A function that can return multiple values simultaneously.
An object that represents the eventual completion (or failure) of an asynchronous operation.
A conditional structure that evaluates boolean values.
A type of loop used to iterate over array elements.

What is the difference between == and === in JavaScript?

== compares values, but === compares both data types and values.
== compares both data types and values, but === only compares values.
There is no difference; both perform the same comparison.
== compares only numbers, while === compares strings.

What is the "event loop" in JavaScript?

It is an execution cycle that repeats endlessly until the code finishes.
It is a mechanism that executes asynchronous tasks in the browser's main thread.
It is a method that stops the execution of code until the task completes.
It is an algorithm used to sort data efficiently.

What is a "closure" in JavaScript?

A function that accesses variables from its external environment even after the environment has finished executing.
A function that runs immediately after being defined.
A method for handling errors in JavaScript.
A way to create private variables within an object.

What does the "this" keyword do in JavaScript?

Refers to the global object, regardless of context.
Refers to the object in which the function was called.
Refers to the value returned by the function.
Has no value, it is simply a placeholder.

How do you handle errors in JavaScript?

Using catch only.
Using try, catch, and finally.
Using finally only.
Using throw only.

What is the difference between pure and impure functions?

Pure functions have no side effects, while impure functions do.
Impure functions cannot return values.
Pure functions are slower than impure ones.
There is no difference between pure and impure functions.

What is the "spread operator" in JavaScript?

A method to iterate over array elements.
A function used to split an object into multiple objects.
An operator that spreads an iterable into individual elements.
An operator that allows copying elements from one object to another.

What is JSX in React?

A JavaScript extension that allows writing HTML within JavaScript code.
A type of database to store React components.
An additional library to optimize React.
A compiler that converts HTML into JavaScript.

What is the difference between a class component and a functional component in React?

Class components have a shorter lifespan than functional ones.
Functional components cannot handle state or lifecycle methods.
Class components are more efficient than functional ones.
Functional components cannot use hooks.

What is Redux in React?

A library for managing state in React applications.
A package for server-side rendering React components.
A tool for creating databases in React applications.
A set of pre-built components for use in React.

How do you handle asynchronous operations in Node.js?

Using promises and the await keyword.
Using setTimeout and setInterval.
Using callbacks only.
Using for loops to control execution.

What is middleware in Express.js?

A mechanism that intercepts and modifies HTTP requests.
A way to secure routes in an application.
An external service that communicates with your Express server.
A method for improving database performance.

What is a RESTful API?

A set of rules for communicating between applications over HTTP using methods like GET, POST, PUT, and DELETE.
A programming language for writing web applications.
A database that communicates with frontend applications.
A cloud-based data storage system.

How can you secure a RESTful API?

By using SSL/TLS and OAuth authentication.
Only by using public keys in requests.
Only by validating user inputs.
By using an encrypted database.

What is CORS (Cross-Origin Resource Sharing)?

A security protocol for sharing resources between different origins.
A service that allows users to share data with multiple applications.
An error that occurs when an application connects to the wrong server.
A method for securing data within a database.

What are NoSQL databases?

Databases that use SQL for queries.
Databases that do not follow a fixed schema and can be more efficient in some cases.
Databases that only store plain text data.
Databases that are easier to manage in large-scale systems.

What is the concept of "callback hell"?

It is a term used when multiple callback functions are nested and hard to manage.
It is an error that occurs when callbacks are used incorrectly.
It is a type of error that happens when a callback returns an incorrect value.
It is the process where callbacks execute sequentially.

TIME LEFT

5:00