Best Practices to Design Javascript Coding Challenges with APIs

Before we begin, let me share a bit about our journey.

At Amadeus for Developers, we offer travel data and services to developers across the world through REST APIs. Thanks to HackerEarth’s platform, we recently hosted the Hack the Journey/Coding India Edition DevOps coding challenge and we invited all developers from India to participate. Since India is one of our main markets, our goal was to allow developers to explore our travel APIs and challenge their knowledge of travel solutions. We designed both theoretical and backend coding challenges, but in this article, we will focus only on the coding part.

The coding challenges were a combination of algorithmic problems and travel technologies. We asked developers to use data from the Amadeus for Developers REST APIs and our SDKs to solve them.

In this article, we will share with you the best practices to build successful Javascript coding challenges with APIs, based on our experience hosting such challenges for global developers.

Use these 6 best practices to design Javascript coding challenges

Let’s explore the 6 best practices that you need for designing Javascript coding challenges for developers:

Steps to Design Javascript Coding Challenges

#1—Define your objective

An essential first step is to define your objectives. When you have that clear in mind, you can build challenges to meet your goals. Some common objectives could be:

Hiring: many companies use coding challenges as part of the recruitment process to identify and evaluate the technical skills of potential candidates.
Awareness: companies build coding challenges to bring awareness to the developer community about their product.
Testing your product: Javascript coding challenges are a great way to allow developers to play with your product. That can bring you valuable feedback and future ideas to improve your product roadmap.

#2—Choose the programming language

One of the key decisions you have to make when you build Javascript coding challenges: which programming language the participants will be required to use. There are several factors to take into consideration in order to identify the most fitting ones:

Top languages: by choosing one of the top languages in the market such as Python, JavaScript, etc. you will attract a larger number of participants.
Company-used languages: if your goal is hiring, you might want to evaluate the participants’ coding skills in  your company’s programming languages
Your familiarity with the language: make sure you are familiar with the language you offer the challenge. That will help you build challenges that fit the language and also better understand the submitted solutions.

For example, in our case, we designed both a Python and Node coding challenge since these are languages we use on a daily basis, but are also the top-used languages for our SDKs. Developers were able to choose to participate in one of these.

Also read: Top 10 Programming Languages of the Future

#3—Define the challenge

The challenge definition is one of the most crucial steps when it comes to the event’s success. Below are some points to consider:

Difficulty level: By providing developers with some warm-up tasks and later on more challenging ones, you give them the opportunity to understand your APIs gradually. Make sure you find the right balance. To ensure the Javascript coding challenges are at the level you are thinking of, it could be useful to ask a colleague to solve them. This will give you an idea of how much time and effort is required to complete the tasks, and allow you to adjust the difficulty accordingly.
Static data: Define challenges that the APIs always return the same data. This will help you to evaluate the solution’s correctness with the unit tests. Since that’s not easy to guarantee, you can build some sandbox environments with static data and coordinate with your API development teams to ensure that the data is not refreshed during the event.

#4—Maximize the efficiency of SDKs

If you provide SDKs as part of your API, you want developers to focus on the challenge solution and use your SDK efficiently, so we would suggest the followings:

Set up the environment: pre-install the SDKs so developers won’t spend time and effort preparing the environment.
Make docs accessible: to make it easy for developers to make their first API call, consider giving them the necessary resources during the challenge.

#5—Ensure API stability

Ensuring the stability of your APIs is essential to let developers solve the given challenges. Here are some points to consider:

Check API stability: If there are any known to you instabilities (eg. backend refresh on specific days) try to avoid the event on these days. If this is not possible, inform the participants about these times to avoid potential disruptions.
Rate limits: don’t forget to consider the API rate limits when you design the Javascript coding challenges. Provide the participants with the necessary documentation or even some helper functions to help them focus on the challenge solution.

Even if instability affects some solutions, it’s not the end of the world. If the developers have hardcoded their solution, make sure you verify their algorithm and any comments they might have left to prove that they were going to arrive at the correct answers despite the instability.

#6—Conduct unit tests

The unit tests are critical to evaluate the submissions and help you find the winners. Some best practices for the unit tests are:

Validate API usage: in order to validate that developers indeed used your API to solve the challenge, write some unit tests to identify the usage of an API key. Also in the file that developers are going to write the code, you can pre-define some variables that are expected to add the API key and secret.
Hide unit test files: this will ensure that developers won’t be able to know what are the expected solutions. Just a tip, it is possible for participants to get through the logs of the unit tests, and in that case, make sure you encrypt them.

Comprehensive list of JavaScript coding challenges

Delving deep into JavaScript requires a mix of theoretical knowledge and hands-on coding practice. Below are various coding challenges, organized by difficulty level and specific concepts, designed to test and improve your JavaScript prowess.

1. Beginner challenges

Basic arithmetic operations:
- Challenge: Create a JavaScript function that takes two numbers as arguments and returns their sum, difference, product, and quotient
- Concept: Basic functions and arithmetic operationsString reversal:
String reversal:
- Challenge: Write a JavaScript function that reverses a string
- Concept: String manipulation
Array duplication:
Challenge: Create a function that removes duplicates from an array
Concept: Array manipulation and iteration

2. Intermediate challenges

Palindrome check:
Challenge: Determine if a given string is a palindrome (reads the same backward as forward, ignoring spaces, punctuation, and capitalization).
Concept: String manipulation and conditional logic
Fibonacci series:
- Challenge: Write a function that generates the first ‘n’ numbers in the Fibonacci series
- Concept: Recursion and iterative solutions
Find the missing number:
- Challenge: Given an array containing n distinct numbers taken from 0, 1, 2, …, n, find the one that is missing from the array
- Concept: Mathematical operations and array manipulation

3. Advanced challenges

Flatten nested array:
- Challenge: Implement a function that flattens a nested array
- Concept: Recursion and array manipulation
Implement bind():
- Challenge: Replicate the functionality of the bind() function without using the built-in function
- Concept: Advanced functions and the ‘this’ keyword
Deep equality check:
- Challenge: Write a function that checks if two objects (and their nested objects) are deeply equal
- Concept: Recursion, object manipulation, and deep comparison

4. Concept-specific challenges

Promises:
- Challenge: Create a mock API call using JavaScript’s Promise
- Concept: Asynchronous programming and Promises
Closures:
- Challenge: Design a function that generates a series of functions to add n to their argument, where n is the order in which they were generated
- Concept: Closures and function factories
DOM Manipulation:
- Challenge: Build a simple JavaScript-based to-do list with add, delete, and mark as completed functionalities
- Concept: DOM manipulation and event handling

Additional tips for solving JavaScript coding challenges

While the right logic and approach are essential for solving coding challenges, there are several other aspects that can enhance your problem-solving journey, especially when using JavaScript. Here are some additional pointers:

Before jumping into the code, make sure you understand the problem thoroughly. It might help to write down or discuss the problem with someone else or even talk aloud to yourself. Often, solutions emerge from a deeper understanding.
If a problem seems too complex, break it down into smaller components or steps. This modular approach can make the overall challenge more manageable and can aid in systematic problem solving.
JavaScript has a plethora of built-in methods, especially for arrays and strings. Familiarize yourself with these, but also know when they might be overkill. Sometimes a simpler approach might be more efficient and more readable.
When solving a challenge, think about potential edge cases. For example, consider empty strings, arrays, or the minimum and maximum possible inputs.
Use console.log() extensively to understand the flow of your code and to pinpoint issues. Developer tools in browsers can also provide insights into the execution of your JavaScript code.
Your first solution doesn’t always have to be the most efficient. It’s okay to arrive at a working solution first and then iterate on it to make it better.
Like any skill, coding gets better with regular practice. Regularly engage with coding platforms, participate in coding challenges, and always strive to learn from your mistakes.
JavaScript, like all languages, evolves. Stay updated with the latest ECMAScript specifications and new methods or features that might be introduced.
Join coding forums or communities where you can post your solutions and receive feedback. Sometimes, there are multiple ways to solve a problem, and seeing others’ solutions can provide new perspectives.
Frustration can be a natural part of the problem-solving process. If you’re stuck, take a break. Sometimes, stepping away and coming back with a fresh mind can make all the difference.

Also read: How to Create a Great Take-Home Coding Test?

Create Javascript coding challenges with HackerEarth

To sum up, it’s crucial to carefully consider several factors when creating challenges that require developers to use APIs to reach the problem solution. By following best practices such as ensuring API stability, building the right unit tests, and providing necessary resources, you can create successful Javascript coding challenges that allow developers to explore and test their knowledge of your APIs. Lastly, don’t hesitate to ask HackerEarth for support and advice. Thanks to them, we were able to solve many of our doubts and build a successful coding challenge together.

We hope that these tips will be useful for your own journey.

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Hackathons

Vibe Coding: Shaping the Future of Software

A New Era of Code

Vibe coding is a new method of using natural language prompts and AI tools to generate code. I have seen firsthand that this change makes software more accessible to everyone. In the past, being able to produce functional code was a strong advantage for developers. Today, when code is produced quickly through AI, the true value lies in designing, refining, and optimizing systems. Our role now goes beyond writing code; we must also ensure that our systems remain efficient and reliable.

From Machine Language to Natural Language

I recall the early days when every line of code was written manually. We progressed from machine language to high-level programming, and now we are beginning to interact with our tools using natural language. This development does not only increase speed but also changes how we approach problem solving. Product managers can now create working demos in hours instead of weeks, and founders have a clearer way of pitching their ideas with functional prototypes. It is important for us to rethink our role as developers and focus on architecture and system design rather than simply on typing code.

The Promise and the Pitfalls

I have experienced both sides of vibe coding. In cases where the goal was to build a quick prototype or a simple internal tool, AI-generated code provided impressive results. Teams have been able to test new ideas and validate concepts much faster. However, when it comes to more complex systems that require careful planning and attention to detail, the output from AI can be problematic. I have seen situations where AI produces large volumes of code that become difficult to manage without significant human intervention.

AI-powered coding tools like GitHub Copilot and AWS’s Q Developer have demonstrated significant productivity gains. For instance, at the National Australia Bank, it’s reported that half of the production code is generated by Q Developer, allowing developers to focus on higher-level problem-solving . Similarly, platforms like Lovable enable non-coders to build viable tech businesses using natural language prompts, contributing to a shift where AI-generated code reduces the need for large engineering teams. However, there are challenges. AI-generated code can sometimes be verbose or lack the architectural discipline required for complex systems. While AI can rapidly produce prototypes or simple utilities, building large-scale systems still necessitates experienced engineers to refine and optimize the code.

The Economic Impact

The democratization of code generation is altering the economic landscape of software development. As AI tools become more prevalent, the value of average coding skills may diminish, potentially affecting salaries for entry-level positions. Conversely, developers who excel in system design, architecture, and optimization are likely to see increased demand and compensation.
Seizing the Opportunity

Vibe coding is most beneficial in areas such as rapid prototyping and building simple applications or internal tools. It frees up valuable time that we can then invest in higher-level tasks such as system architecture, security, and user experience. When used in the right context, AI becomes a helpful partner that accelerates the development process without replacing the need for skilled engineers.

This is revolutionizing our craft, much like the shift from machine language to assembly to high-level languages did in the past. AI can churn out code at lightning speed, but remember, “Any fool can write code that a computer can understand. Good programmers write code that humans can understand.” Use AI for rapid prototyping, but it’s your expertise that transforms raw output into robust, scalable software. By honing our skills in design and architecture, we ensure our work remains impactful and enduring. Let’s continue to learn, adapt, and build software that stands the test of time.

Ready to streamline your recruitment process? Get a free demo to explore cutting-edge solutions and resources for your hiring needs.

Tech Assessment

Guide to Conducting Successful System Design Interviews in 2025

What is Systems Design?

Systems Design is an all encompassing term which encapsulates both frontend and backend components harmonized to define the overall architecture of a product.

Designing robust and scalable systems requires a deep understanding of application, architecture and their underlying components like networks, data, interfaces and modules.

Systems Design, in its essence, is a blueprint of how software and applications should work to meet specific goals. The multi-dimensional nature of this discipline makes it open-ended – as there is no single one-size-fits-all solution to a system design problem.

What is a System Design Interview?

Conducting a System Design interview requires recruiters to take an unconventional approach and look beyond right or wrong answers. Recruiters should aim for evaluating a candidate’s ‘systemic thinking’ skills across three key aspects:

How they navigate technical complexity and navigate uncertainty
How they meet expectations of scale, security and speed
How they focus on the bigger picture without losing sight of details

This assessment of the end-to-end thought process and a holistic approach to problem-solving is what the interview should focus on.

What are some common topics for a System Design Interview

System design interview questions are free-form and exploratory in nature where there is no right or best answer to a specific problem statement. Here are some common questions:

How would you approach the design of a social media app or video app?

What are some ways to design a search engine or a ticketing system?

How would you design an API for a payment gateway?

What are some trade-offs and constraints you will consider while designing systems?

What is your rationale for taking a particular approach to problem solving?

Usually, interviewers base the questions depending on the organization, its goals, key competitors and a candidate’s experience level.

For senior roles, the questions tend to focus on assessing the computational thinking, decision making and reasoning ability of a candidate. For entry level job interviews, the questions are designed to test the hard skills required for building a system architecture.

The Difference between a System Design Interview and a Coding Interview

If a coding interview is like a map that takes you from point A to Z – a systems design interview is like a compass which gives you a sense of the right direction.

Here are three key difference between the two:

Coding challenges follow a linear interviewing experience i.e. candidates are given a problem and interaction with recruiters is limited. System design interviews are more lateral and conversational, requiring active participation from interviewers.

Coding interviews or challenges focus on evaluating the technical acumen of a candidate whereas systems design interviews are oriented to assess problem solving and interpersonal skills.

Coding interviews are based on a right/wrong approach with ideal answers to problem statements while a systems design interview focuses on assessing the thought process and the ability to reason from first principles.

How to Conduct an Effective System Design Interview

One common mistake recruiters make is that they approach a system design interview with the expectations and preparation of a typical coding interview.
Here is a four step framework technical recruiters can follow to ensure a seamless and productive interview experience:

Step 1: Understand the subject at hand

Develop an understanding of basics of system design and architecture
Familiarize yourself with commonly asked systems design interview questions
Read about system design case studies for popular applications
Structure the questions and problems by increasing magnitude of difficulty

Step 2: Prepare for the interview

Plan the extent of the topics and scope of discussion in advance
Clearly define the evaluation criteria and communicate expectations
Quantify constraints, inputs, boundaries and assumptions
Establish the broader context and a detailed scope of the exercise

Step 3: Stay actively involved

Ask follow-up questions to challenge a solution
Probe candidates to gauge real-time logical reasoning skills
Make it a conversation and take notes of important pointers and outcomes
Guide candidates with hints and suggestions to steer them in the right direction

Step 4: Be a collaborator

Encourage candidates to explore and consider alternative solutions
Work with the candidate to drill the problem into smaller tasks
Provide context and supporting details to help candidates stay on track
Ask follow-up questions to learn about the candidate’s experience

Technical recruiters and hiring managers should aim for providing an environment of positive reinforcement, actionable feedback and encouragement to candidates.

Evaluation Rubric for Candidates

Facilitate Successful System Design Interview Experiences with FaceCode

FaceCode, HackerEarth’s intuitive and secure platform, empowers recruiters to conduct system design interviews in a live coding environment with HD video chat.

FaceCode comes with an interactive diagram board which makes it easier for interviewers to assess the design thinking skills and conduct communication assessments using a built-in library of diagram based questions.

With FaceCode, you can combine your feedback points with AI-powered insights to generate accurate, data-driven assessment reports in a breeze. Plus, you can access interview recordings and transcripts anytime to recall and trace back the interview experience.

Learn how FaceCode can help you conduct system design interviews and boost your hiring efficiency.

AI Recruiting

How Candidates Use Technology to Cheat in Online Technical Assessments

Impact of Online Assessments in Technical Hiring

In a digitally-native hiring landscape, online assessments have proven to be both a boon and a bane for recruiters and employers.

The ease and efficiency of virtual interviews, take home programming tests and remote coding challenges is transformative. Around 82% of companies use pre-employment assessments as reliable indicators of a candidate's skills and potential.

Online skill assessment tests have been proven to streamline technical hiring and enable recruiters to significantly reduce the time and cost to identify and hire top talent.

In the realm of online assessments, remote assessments have transformed the hiring landscape, boosting the speed and efficiency of screening and evaluating talent. On the flip side, candidates have learned how to use creative methods and AI tools to cheat in tests.

As it turns out, technology that makes hiring easier for recruiters and managers - is also their Achilles' heel.

Cheating in Online Assessments is a High Stakes Problem

With the proliferation of AI in recruitment, the conversation around cheating has come to the forefront, putting recruiters and hiring managers in a bit of a flux.

According to research, nearly 30 to 50 percent of candidates cheat in online assessments for entry level jobs. Even 10% of senior candidates have been reportedly caught cheating.

The problem becomes twofold - if finding the right talent can be a competitive advantage, the consequences of hiring the wrong one can be equally damaging and counter-productive.

As per Forbes, a wrong hire can cost a company around 30% of an employee's salary - not to mention, loss of precious productive hours and morale disruption.

The question that arises is - "Can organizations continue to leverage AI-driven tools for online assessments without compromising on the integrity of their hiring process? "

This article will discuss the common methods candidates use to outsmart online assessments. We will also dive deep into actionable steps that you can take to prevent cheating while delivering a positive candidate experience.

Common Cheating Tactics and How You Can Combat Them

Using ChatGPT and other AI tools to write code
Copy-pasting code using AI-based platforms and online code generators is one of common cheat codes in candidates' books. For tackling technical assessments, candidates conveniently use readily available tools like ChatGPT and GitHub. Using these tools, candidates can easily generate solutions to solve common programming challenges such as:
- Debugging code
- Optimizing existing code
- Writing problem-specific code from scratch
Ways to prevent it
- Enable full-screen mode
- Disable copy-and-paste functionality
- Restrict tab switching outside of code editors
- Use AI to detect code that has been copied and pasted
Enlist external help to complete the assessment

Candidates often seek out someone else to take the assessment on their behalf. In many cases, they also use screen sharing and remote collaboration tools for real-time assistance.

In extreme cases, some candidates might have an off-camera individual present in the same environment for help.

Ways to prevent it
- Verify a candidate using video authentication
- Restrict test access from specific IP addresses
- Use online proctoring by taking snapshots of the candidate periodically
- Use a 360 degree environment scan to ensure no unauthorized individual is present
Using multiple devices at the same time

Candidates attempting to cheat often rely on secondary devices such as a computer, tablet, notebook or a mobile phone hidden from the line of sight of their webcam.

By using multiple devices, candidates can look up information, search for solutions or simply augment their answers.

Ways to prevent it
- Track mouse exit count to detect irregularities
- Detect when a new device or peripheral is connected
- Use network monitoring and scanning to detect any smart devices in proximity
- Conduct a virtual whiteboard interview to monitor movements and gestures
Using remote desktop software and virtual machines

Tech-savvy candidates go to great lengths to cheat. Using virtual machines, candidates can search for answers using a secondary OS while their primary OS is being monitored.

Remote desktop software is another cheating technique which lets candidates give access to a third-person, allowing them to control their device.

With remote desktops, candidates can screen share the test window and use external help.

Ways to prevent it
- Restrict access to virtual machines
- AI-based proctoring for identifying malicious keystrokes
- Use smart browsers to block candidates from using VMs

Future-proof Your Online Assessments With HackerEarth

HackerEarth's AI-powered online proctoring solution is a tested and proven way to outsmart cheating and take preventive measures at the right stage. With HackerEarth's Smart Browser, recruiters can mitigate the threat of cheating and ensure their online assessments are accurate and trustworthy.

Secure, sealed-off testing environment
AI-enabled live test monitoring
Enterprise-grade, industry leading compliance
Built-in features to track, detect and flag cheating attempts

Boost your hiring efficiency and conduct reliable online assessments confidently with HackerEarth's revolutionary Smart Browser.

6 Best Practices to Design Javascript Coding Challenges with APIs