Hire ExpressJS Developers In 72 Hours

Flexiple is a network of top ExpressJS developers, engineers, and architects with hourly rates ranging from $30 to $100. Hire ExpressJS developers from Flexiple for a few weeks to a few years and join 100+ teams who have built amazing products!
CHISIMDI DAMIAN EZEANIETO

CHISIMDI DAMIAN EZEANIETO

ExpressJS Developer

WORKED AT

Naya Labs
PAUL OLDENBURGER

PAUL OLDENBURGER

ExpressJS Developer

WORKED AT

Usetech
KUSHAGRA SHARMA

KUSHAGRA SHARMA

ExpressJS Developer

WORKED AT

PayPal
EDWIN ROSEMBERT

EDWIN ROSEMBERT

Senior ExpressJS Developer

WORKED AT

Affirm
RAFAEL BONALUME LEBRE

RAFAEL BONALUME LEBRE

ExpressJS Developer

WORKED AT

MDMED

Flexiple spent good amount of time understanding our requirements, resulting in accurate recommendations and quick ramp up by quality developers.

Narayan Vyas, Senior PM (YC S12)

Overall Flexiple brought in high-level of transparency with quick turnarounds in the hiring process at a significantly lower cost than any alternate options.

Esther Hersh, Co-founder ('17 NYU Grad)

Flexiple has been instrumental in helping us grow at a fast pace. Their vetting process for engineers is top notch and they connected us with quality talent quickly.

Tanu V, Founder (#1 Salesforce Leads App)

Work With Flexiple's Expert ExpressJS Developers!

Be a short-term or a long-term project, don't compromise on the quality of talent you work with. Flexiple handpicks only the Top 1% through a 6-stage screening process.
  • KARAN BHOMIA
    KARAN BHOMIA
    ExpressJS MogoDB Java

    Karan is a backend developer with over 7 years of experience in the software industry. He is a highly capable professional with experience in server-side ... Karan is a backend developer with over 7 years of experience in the software industry. He is a highly capable professional with experience in server-side development using Golang, PostreSQL, NoSQL, among others. He is incredibly proficient working under Agile development methodology. Karan loves to build enterprise products from the ground up with a focus to deliver quality products at the end of the day. Read MoreRead Less

    Worked at Oracle

    Hire Karan
  • GERALD ANOSIKE
    GERALD ANOSIKE
    ExpressJS NodeJS DevOps

    Gerald is a skilled backend developer with 4 years of experience in the software development industry. He specializes in skills such as NodeJS, ExpressJS, MongoDB, ... Gerald is a skilled backend developer with 4 years of experience in the software development industry. He specializes in skills such as NodeJS, ExpressJS, MongoDB, and PostgreSQL among others. Over the past few years, Gerald has worked as both an individual contributor and a team player on multiple projects. He is also comfortable with cloud-related techs such as AWS and Azure. Read MoreRead Less

    Worked at Venture Garden Group

    Hire Gerald
  • CHISIMDI DAMIAN EZEANIETO
    CHISIMDI DAMIAN EZEANIETO
    ExpressJS NodeJS HTML

    Chisimdi is a detail-oriented full stack developer with over 5 years of experience with web technologies. His experience in software development has availed him with ... Chisimdi is a detail-oriented full stack developer with over 5 years of experience with web technologies. His experience in software development has availed him with the ability to refactor spaghetti code into reusable, testable, and trustworthy software programs. With a vast skillset paired with a genuine love of technology, Chisimdi has an interest towards Artificial Intelligence and Robotics Read MoreRead Less

    Worked at Naya Labs

    Hire Chisimdi
  • PAUL OLDENBURGER
    PAUL OLDENBURGER
    ExpressJS Bootstrap Angular

    Paul is a full stack developer with 4 years of experience and is an adept in various frameworks like Angular, ReactJS, NodeJS, among others. He ... Paul is a full stack developer with 4 years of experience and is an adept in various frameworks like Angular, ReactJS, NodeJS, among others. He is a creative problem solver who places an emphasis on quality building, efficient optimizing, and testing of web applications. He is an active participant in multiple hackathons and community projects where he uses his analytical skills to create dynamic applications. Read MoreRead Less

    Worked at Usetech

    Hire Paul
  • KUSHAGRA SHARMA
    KUSHAGRA SHARMA
    Expressjs html python

    An adroit full-stack developer with over 5 years of experience, Kushagra is an expert in ReactJS, NodeJS, Python,etc. His work at prominent product companies like ... An adroit full-stack developer with over 5 years of experience, Kushagra is an expert in ReactJS, NodeJS, Python,etc. His work at prominent product companies like PayPal is a testament to his proficiency. He is skilled at building, maintaining complex large scale production systems.Having worked on refactoring, testing, monitoring, his vast knowledge comes handy in mentorship roles. Read MoreRead Less

    Worked at PayPal

    Hire Kushagra
  • SANTU MAHAPATRA
    SANTU MAHAPATRA
    ExpressJS Javascript Python

    A Senior Developer with over 10 years of industry experience, Santu has worked both as a Tech Lead and an Individual Contributor. He has built ... A Senior Developer with over 10 years of industry experience, Santu has worked both as a Tech Lead and an Individual Contributor. He has built various server-side applications on a diverse tech stack and also has experience in building Mobile and Web apps using various JavaScript libraries. Santu is dedicated towards creating great user experiences in software and loves to simplify technology for usability. Read MoreRead Less

    Worked at Compro Technologies

    Hire Santu
  • EDWIN ROSEMBERT
    EDWIN ROSEMBERT
    ExpressJS NodeJS React

    Edwin is a senior software engineer with 8 years of experience developing software products using JS frameworks. He is skilled in several back-end languages and ... Edwin is a senior software engineer with 8 years of experience developing software products using JS frameworks. He is skilled in several back-end languages and framework to deliver robust, performant API back ends and the clients and applications they serve. Edwin is a specialist who provides effective solutions by using best practices and pragmatic methods bundled with his mastery of business and technical skills Read MoreRead Less

    Worked at Affirm

    Hire Edwin
  • RAFAEL BONALUME LEBRE
    RAFAEL BONALUME LEBRE
    ExpressJS Docker GraphQL

    Rafael is a full stack software engineer with 6 years of experience in the software industry. He is a competent developer with expertise in various ... Rafael is a full stack software engineer with 6 years of experience in the software industry. He is a competent developer with expertise in various languages such as PHP, Javascript, HTML, and their various libraries and frameworks. He can quickly pick up new technologies with a focus on implementing them to solve the problems at hand. He is a result oriented professional with a passion for learning. Read MoreRead Less

    Worked at MDMED

    Hire Rafael

Flexiple Helps You Hire Quality ExpressJS Developers, Handpicked For You

  • Work only with the best

    Our developers are selected through a 6-stage screening process. As a result, our developers have an average of 5-years industry experience and are ready to immediately contribute on projects.
  • Work with Role-specific Developers

    Save time and energy lost in manually sifting through profiles. Our solutions expert along with our Director of Technology will handpick developers who are a perfect match for your requirement.
  • Work Risk-free & Start within 2 Days

    With immense confidence in the quality of our developers and the accuracy of our recommendations, we are happy to offer you a 2-week trial where you pay only if you are satisfied.

Find The Perfect ExpressJS Developer For Your Team At The Right Price

  • Individual Contributor

    $
    /year
    $30-50
    /hour
    • 1-3 years of experience
    • Mostly worked on a single stack
    • Top Individual Contributor
  • Multi-faceted Contributor

    $
    /year
    $50-80
    /hour
    • 3-7 years of experience
    • Expertise in multiple stacks
    • Worked on niche skills
    • Mentors Junior Developers
  • Leader & Diverse Contributor

    $
    /year
    $80+
    /hour
    • 7-10+ years of experience
    • Worked across stacks, products
    • Multiple niche skills
    • Led multiple teams in the past

How We Select the Top 1%

45.4%pass rate

Depth in past work

Flexiple Developers are reviewed on their experience and complexity of products built. Those who display depth and have worked on end-to-end projects are given an introductory call.

14.6%pass rate

Good communication and motivation

Over a call, the developer’s ability to communicate in an articulate manner is tested. A deeper understanding of the candidate’s technical experience and also motivation to freelance is achieved.

3.1%pass rate

Strong technical abilities

Over one or more F2F interviews, the developer’s involvement and performance in building complex software products are assessed. This sets the platform to delve deeper into technology-specific discussions.

1.5%pass rate

Keen problem solving and coding

Developers' mental agility and problem-solving abilities are tested through a coding test involving algorithmic as well as skill-specific problems. A mixture of live evaluation and timed coding tests is used.

1.2%pass rate

Splendid reviews in background check

The live experience of working with developers is verified by reaching out to past clients and/or employers. Inputs on various qualitative factors such as reliability, punctuality, communication and responsiveness are received.

1%pass rate

Consistent exemplary performance

Performance during each engagement is continually assessed. Our developers are expected to maintain Flexiple standards across all engagements with our customers.

Hire ExpressJS Developers Within 72 Hours!

Our simple process gets you working with the right freelancer quickly and seamlessly

Don't Just Take Our Word For It!

(Y-Combinator S12 and Andreessen Horowitz-backed Company)

Quality product launched on schedule by a team of 8 engineers

"Flexiple helped us hire quality developers across technologies - Node, Rails, PHP, Python. They spent a good amount of time understanding our requirements, resulting in accurate recommendations and quick ramp up by developers. We also found them to be much more affordable than other alternatives for the same level of quality."

Narayan Vyas,

Senior Product manager, Plivo Inc

(Incubated at the European Space Agency)

Helped set up and scale tech team on demand

"Flexiple has exceeded our expectations with their focus on customer satisfaction! The freelancers are brilliant at what they do and have made an immense impact. Highly recommended :)"

Henning Grimm,

Founder, Aquaplot

(Acquired by Unicorn, Hike Messenger)

Saved 30% costs with 2 software products delivered

“Overall Flexiple brought in high-level of transparency with extremely quick turnarounds in the hiring process at a significantly lower cost than any alternate options we had considered.”

Kislay Shashwat,

VP Finance, CREO

('17 NYU Graduates)

Found a perfect new member for its globally distributed team

"Working with Flexiple has provided us with partners who are providing us with the required technical support for our growth and success!"

Esther Hersh,

Co-founder, Peblio Inc

(Y-Combinator S18)

Hired the first remote engineer to work directly with the CTO

"It has been great working with Flexiple for hiring highly talented and hardworking folks on contract. We were looking for a suitable developer on the back-end and we got to know Ankur through Flexiple. We are very happy with the commitment and skills he brings to the job and we will be working with Flexiple going forward as well after this positive experience. I recommend them highly for any freelancing talent you are looking to hire!"

Neil Shah,

Chief of Staff, Prodigal Tech

(#1 Lead Routing App for Salesforce)

Helped scale the product with a team of engineers

"Flexiple has been instrumental in helping us grow at a fast pace. Their vetting process for engineers is top notch and they were able to connect us with quality talent quickly. The team put great emphasis in understanding our requirements and getting to know us which ensured that we were matched with folks who were a great fit not only technically but also culturally."

Tanu V,

Founder, Power Router

(Acquired by Reliance for $100 million)

Delivered 2 high quality products forming a long partnership

"The engagement with Flexiple and their community members has helped us get work done in a timely manner and helped us go above and beyond."

Swapan R,

Co-founder, Haptik

(Acquired by PayU for $70 million)

Built their first remote tech team of a frontend and backend engineer

"Highly responsive team with prompt support and willingness to go the extra mile. Powered by technically brilliant personnel on board, we have happy results – all this at an affordable price!"

Sajith N,

Product Manager, Wibmo Inc
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Frequently Asked Questions

  • How To Find The Best ExpressJS Developers For Hire?

  • Express Javascript i.e ExpressJS is a backend web application framework for NodeJS. Released as an open source and free software, it is one of the most popular NodeJS frameworks used for developing features for mobile and web applications.

    It is preferred by programmers on a time crunch - who do not want to undertake a lot of coding without compromising on quality. ExpressJS is used by companies around the world primarily for enterprise app development. Some notable names include Paypal, Uber, Accenture, IBM.

    If you’re looking to hire ExpressJS developers for your company, this guide is going to help you find the perfect fit. We’ve included everything you need to know about hiring a freelance ExpressJS developer.

    1.Let's introduce ExpressJS to you

    • ExpressJS was founded by  TJ Holowaychuk back in May 22nd 2010 to help create APIs and web applications with ease.
    • Inspired by the open source software Sinatra, Holowaychuk developed ExpressJS which required relatively minimal coding and could incorporate many features as plugins.
    • In June 2014, Holowaychuk sold the rights of open source ExpressJS to a Node.js based startup called StrongLoop.
    • StrongLoop was then acquired by IBM by 2015, and by 2016, IBM handed off Express to the NodeJS foundation.
    • ExpressJS is currently managed and maintained by the NodeJS foundation.

    2. Why is ExpressJS widespread?

    • ExpressJS' popularity can be attributed to its pre-built Node framework which enable programmers to develop intelligent applications faster.
    • ExpressJS is also highly extensible via NodeJS. This improves the scalability of your applications with your desired features by adding more resources to your framework.
    • Since Express is a fullstack JavaScript framework, it also requires lesser maintenance and development cost, making it a more cost effective option compared to its counterparts.

    3. Writing the job description to hire ExpressJS developers

    Below are some key points that we at Flexiple have learned through trial and error - a process of filtering through over 15,000 developers. You can use these in your process to hire JavaScript developers.

    • Years of software development experience: Be specific about the technology you’re looking for and the number of years of experience needed. A proxy to years of experience can be the number of production-level apps worked on.
    • Type of products built in the past: Based on the type of product you are trying to build - social network, SAAS product, etc. - you can prioritize certain developers over others.
    • Exposure to specific industries: Developers who have built products in certain industries will already know key aspects of laying the foundation for a great product and will be able to predict possible problems.
    • Experience working remotely: A developer with past remote work experience is an added advantage as they would have first-hand experience of everything - right from how contracts work to streamlined communication, as well as timelines and deliverables.
    • Strong communication: An essential thing to look at when hiring a freelancer is excellent communication skills. Since all the interaction happens online, a freelancer should be able to effectively communicate to ensure a streamlined execution of all work.
    • 4. Interview Questions to hire ExpressJS Developer

      Now that you have made a quality JD, it can still be tricky to evaluate the skills of your applicants when you hire ExpressJS developers. To help you with that, we have created a pool of questions that a good software developer should be comfortable with.

      It is important to note that the ability to answer these questions doesn't imply that you have a top quality candidate. But it definitely is a big step in that direction.

      To help you navigate through these questions, we’ve categorized the interview questions in 3 parts:

      A. Basic concepts: Includes all basic concepts used across languages but we've focused on their significance in Node.js. This will give you an understanding of how strong their programming foundation is.

      B. Advanced concepts: Includes all concepts that someone with higher expertise should know.

      C. DS/Algorithm questions: To test the logical capability of the candidate.

      A. Basic concepts

  • How is NodeJS asynchronous when javascript is single-threaded ?

    We first need to understand that NodeJS is just a Javascript runtime built on Chrome’s V8 engine. The V8 engine was originally made by Google for Google. It was written in C++ to compile Javascript functions to machine code. It is highly efficient and optimised and is also used in Google Chrome for the same purpose.

    Javascript is a single threaded language. This means that it has one call stack and one memory heap. Due to this it has to execute code sequentially. But as we know, the devils of synchronous programming can often decrease the efficiency of code. This is primarily due to blocking code which takes a long time to execute, such as I/O operations.

    Request Handling in Browsers

    To combat this problem, we have the different browser engines such as Chrome’s V8 engine, Firefox’s Spidermonkey, etc.. Tasks which take a long time are handled by Web API of these engines, which handle them in the background and allow synchronous execution of the rest of the code. When the background task in the Web API is done, a callback is pushed to the call stack.

    Multi-threaded Request-Response Architecture

    In other popular web application technologies such as JSP, Spring, ASP.NET, the language spawns a thread for each request and the thread executes the request and sends back a response. This is known as Multi-threaded Request-Response architecture.

    Single-threaded Event Loop Architecture

    NodeJS on the other hand follows a path similar to Javascript. NodeJS follows Single-threaded Event Loop architecture. It is built upon Javascript’s event based model with its callback mechanism.

    The NodeJS web server internally maintains a thread pool to handle client requests, but these are not meant to be handled and used by the developer directly. The number of threads in the thread pool depends on the number of cores the CPU has. When the web server receives the requests, they are added to a queue known as ‘Event Queue’.

    ‘Event Loop’ is yet another internal component which is central to this architecture of NodeJS. Event Loop uses a single thread only. It runs indefinitely and checks the Event Queue for requests. If the request does not require any blocking I/O operation like handling file system, database, then the single thread directly executes them. But if there is any such operation then a thread is picked up from the thread pool, assigned to the request, and when it finishes puts a callback in the Event Loop.

    Therefore, NodeJS runs on a single thread, similar to Javascript, but it maintains a thread pool from which it spawns threads to run asynchronous functions in the background.

    B. Advanced concepts

  • What is a load balancer and how will you set it up?

    First let us discuss why load balancers are required. As the traffic increases on a server, the server experiences a slow down. To prevent this slow down, the server needs to be scaled up. Scaling of server can be achieved in two ways:

    1. Vertical Scaling
    2. Horizontal Scaling

    Vertical scaling refers to upgrading the resources of a particular server by increasing storage, increasing RAM, upgrading CPU. This gives the server more cores, faster execution speed, faster access time to storage and more storage. This was largely the traditional way of increasing performance of a server.

    Horizontal scaling refers to using multiple servers to increase the performance of the back end infrastructure. So, instead of boosting resources of one server, multiple servers are used together. This has been found to be cheaper than vertical scaling and therefore practiced on a large scale. A load balancer is, thus, required in case of horizontal scaling.

    In software development, load balancing refers to the process of distributing a set of tasks over a set of resources, with the aim of making their overall processing more efficient. Coming to backend development, load balancing refers to efficiently distributing incoming network traffic across a group of backend servers. Such a group of servers is called a server farm or server pool.

    Along with distributing traffic load balancers also help in preventing a server from becoming a single point of failure. In a large scale architecture load balancers can be placed at 3 levels:

    • between client and web server
    • between web server and internal platform layer (like cache server or application server)
    • between internal platform layer and database

    But we are primarily going to focus on the first one.

    Working

    One server is taken primarily for load balancing. The requests first hit this server and then based on the load balancing algorithm the request is routed to one of the several back end servers, which carry out the request.

    A load balancer considers two factors before forwarding a request:

    • An algorithm that helps in choosing from the healthy servers
    • If the server chosen is responding appropriately

    The different algorithms used by a load balancer are:

    1. Least Connection Method: Direct traffic to the server with fewest active connections
    2. Least Response Time Method: Direct traffic to the server with fewest active connections and least response time
    3. Least Bandwidth Method: Direct traffic to the server serving the least amount of traffic (measured in Mbps)
    4. Round Robin Method: Directs requests to servers in a cyclic manner
    5. Weighted Round Robin Method: Different servers are weighed according to their resources, accordingly the one with more weights is given more priority.
    6. IP Hash: A hash is calculated of the IP address of the client. The server to forward the request to is chosen based on the hash value. 

    NGINX

    A popular software used for load balancing is NGINX. It is an open source software for web serving, reverse proxying, caching, load balancing, media streaming, and more. It started out as a web server designed for maximum performance and stability. In addition to its HTTP server capabilities, NGINX can also function as a proxy server for email (IMAP, POP3, and SMTP) and a reverse proxy & load balancer for HTTP, TCP, and UDP servers.

    It is quite simple to use NGINX as a load balancer. Install NGINX in the server chosen to be as the load balancer.

    upstream app_servers {     
        server backend1.example.com; 
        server backend2.example.com; 
        server backend3.example.com; 
    }  
    server {
            listen       80;
            server_name  localhost;
    
    location / {
       proxy_set_header X-Real-IP $remote_addr;
       proxy_set_header Host      $http_host;
       proxy_pass       http://app_servers;
    }
    }  

    The upstream app_server block holds the servers to redirect requests to. Inside the location block, we are setting app_server as the target block. The server_name identifies which domain the load balancer will show.

  • Give a detailed overview of any one authentication strategy?

    Web apps need to be authenticated to ensure that only the required people get access to the required data. Without strong authentication, you can suffer problems ranging from unauthorized login to complete leak of the database.

    Authentication strategies are methods for user authentication and management. There are multiple ways to achieve this. With a constantly shifting landscape, it is difficult to zero in on one strategy as the best. Yet, it is a necessary element of almost all real world NodeJS projects.

      The authentication strategies in NodeJS can broadly be classified into 3 types:
    • Middleware Modules (like Passport.js)
    • User Management as a Service
    • Custom Database and Authentication

    Middleware Modules

    These are npm packages such as Passport.js, Everyauth and Permit. These are packages that work on top of NodeJS frameworks such as Express.js, Koa.js, Hapify.js. They utilise the ‘connect’ middleware conventions. This means that while using the aforementioned frameworks, you can just plug in the modules and use their functionality.

    These mainly deal with session management, and also provide single sign on features. But their functionality is largely limited to this. They do not provide other features like account verification and password reset, which are left to the developer to develop.

    Passport.js is by far the most popular amongst these packages. It is an authentication middleware designed primarily to authenticate requests and to safeguard endpoints/routes from unknown users. It can be implemented within an Express-based NodeJS web application.

    Today, there are multiple ways of providing authentication: like a simple sign up/login or single-sign-on using an OAuth provider such as Facebook or Github, etc.. Passport offers a varied set of such mechanisms in the form of different packages, so that the developer doesn’t have to be burdened with extra dependencies.

    app.post('/login', passport.authenticate('local', { successRedirect: '/',
                                                        failureRedirect: '/login' }));  

    As you can see in this route, passport.authenticate() is a middleware in the Express app route. In the passport authentication, ‘local’ option is opted which means using a custom username and password instead of OAuth through Facebook, Twitter or any other such provider. If the authentication is successful, then the user is redirected to the route ‘/’ and if it fails then the user is redirected to ‘/login’.

    User Management as a Service

    These are services such as Stormpath/Okta, Keycloak and Auth0. Over time, software has moved from on-premise to the cloud, to now a distributed API service. These technologies provide Identity Management APIs for software teams building web, mobile and API driven applications.

    Identity management (ID management) is the organizational process for identifying, authenticating and authorizing individuals or groups of people to have access to applications, systems or networks by associating user rights and restrictions with established identities.

    Such pre-built authentication and user management cut down cost & security risk of developing and maintaining identity in house. As a result, developers can focus on the core features instead. Compared to middleware modules, these provide more features than just securing endpoints. This includes email account verification, password reset workflows, role-based access, two-factor authentication and so on.

    But introducing 3rd party services always has the requirement to be highly available, fast, portable, provide security during transport and most importantly provide flexibility based on the user model. These conditions vary vastly from service to service and an in-depth study needs to be done of all these before adopting a service.

    Stormpath is one such service that offers identity management APIs. It is a cloud-based user data storage system with an option for private deployment. Features include user registration, authentication, authorization, user profiles, single-sign-on, multi-tenancy, token authentication, and API key management. It has an open source SDK present for most popular languages like NodeJS, Angular, Java, PHP, Python, Ruby, .NET, iOS, Android.

    Stormpath also supports easy integration with Passport.js.

    var spClient = new stormpath.Client({ apiKey: apiKey });
     
      // Grab our app, then attempt to create this user's account.
      spClient.getApplication(process.env['STORMPATH_APP_HREF'], function(err, app) {
        if (err) throw err;
     
        app.createAccount({
          givenName: 'John',
          surname: 'Smith',
          username: username,
          email: username,
          password: password,
        }, function (err, createdAccount) {
          if (err) {
            return res.render('register', { title: 'Register', error: err.userMessage });
          }
     
          passport.authenticate('stormpath')(req, res, function () {
            return res.redirect('/dashboard');
          });
        });
      });
    });  

    This showcases a part of how working with Stormpath would be for a developer. Here the createAccount() feature of Stormpath is being showcased. As you can see that Passport.js is also being used and the ‘stormpath’ strategy is chosen.

    Custom Database and Authentication

    This is the more do-it-yourself approach, where the developer builds the whole authentication architecture from scratch. It first starts with choosing your tech stack, database, hashing algorithm, method of maintaining sessions and so on. After this, the next part would be to build the user management service.

    It is a common task as it is intrinsic to almost any real world project. But it is prone to error - as anything built from scratch suffers from. Moreover, there is a hefty amount of code to be maintained too. But this strategy provides the most amount of flexibility and freedom to the developer.

    A traditional stack for achieving this would be to use a database like MongoDB or PostgresQL. Pick the required ORM like sequelize or mongoose with them. Bcrypt is a popular hashing algorithm which also has npm packages for its easy implementation.

    After this, routes need to be created for account creation, user verification, login and password reset. Thereon, an authentication logic is written to secure the different endpoints, and even the database needs to be secured from unauthorized access using secret keys.

    C. Data Structure/ Algorithm

  • 1. Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. An input string is valid if: Open brackets must be closed by the same type of brackets. Open brackets must be closed in the correct order. Note that an empty string is also considered valid.

    class ValidParentheses{
        func isValid(_ s: String) -> Bool {
            var stc = [Character]()
    
            for char in s {
                if char == "(" || char == "[" || char == "{" {
                    stc.append(char)
                } else if char == ")" {
                    guard stc.count != 0 && stc.removeLast() == "(" else {
                        return false
                    }
                } else if char == "]" {
                    guard stc.count != 0 && stc.removeLast() == "[" else {
                        return false
                    }
                } else if char == "}" {
                    guard stc.count != 0 && stc.removeLast() == "{" else {
                        return false
                    }
                }
            }
            return stc.isEmpty
        }
    }
    
    The above code will input 0(false). 
  • 2. What will the output of the following code be?

    var a = 10;
    var b = 5;
    var c = 3;
    if (a / b / c)
         document.write("hi");
    else
        document.write("hello");

    a) hi
    b) hello
    c) error
    d) no output

    The answer is A because the floating-point division returns a non zero value = 0.66 which evaluates
    to true and outputs ‘hi’.

    Hire ExpressJS developers - parting thoughts

    As discussed, it isn't easy to find a quality freelance software developer but this guide makes the process easier for you. To offload the entire hiring process, reach out to us at Flexiple. We've designed a high-quality, 6-step screening process to find the top 1%, freelance developers. You can find the best freelance ExpressJS developers here. We've already served over a hundred clients, earning great reviews for the quality of service.

    Lastly, to quickly summarize it for you:

    • Note your project requirements and hire accordingly. Do not go for the lowest or the highest-paid developer.
    • Don’t hire without vetting- consider asking questions right from the basics to advanced to logical questions.
    • Look for companies like Flexiple that help you find the perfect fit.

    That is everything you need to know for when you want to hire ExpressJS developers. Happy hiring! :)

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