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MERN freelance developer
Rishabh is a software engineer having 7+ years of experience in designing Single Page Applications and mobile applications using MERN stack
MERN freelance developer
Mahesh is a software engineer having 3+ years of experience in developing dynamic single page web applications and mobile apps using MERN stack.
Part-time MERN freelancer
John is a software engineer having 10+ years of experience developing websites and applications using MongoDB, Express, Node, and React.js as the front-end library framework.
Hire dedicated freelance MERN stack developers with UltraGenius
MERN stands for MongoDB, ExpressJS, ReactJS, and NodeJS and is an excellent choice for developing full-stack web applications. MERN stack quickly handles front-end and back-end using high-performance React.js for the front-end which reduces the application’s load-time and Node.js on the backend handling requests asynchronously with its non-blocking I/O. MongoDB is a great choice for database in developing applications which allows freelance MERN developers to store and access data easily through document objects. With the help of Express.js, it becomes easier to configure and customize a web application.
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Want to hire freelance MERN developers on your own? Here are the skills you must look for while hiring a MERN developer
Hiring freelance MERN full stack developers might be an intricate task for you if you are a non-technical manager. Today, MERN is one of the most demanding stack for developing full-stack web applications in the IT industry. But, hiring the most skilled freelance MERN developers among thousands of developers is challenging for anybody. So, here UltraGenius comes to assist you while recruiting the top freelance React.js developers on your own. UltraGenius understands your job requirements and gets you only the top freelance MERN full stack developers who have in-depth knowledge of MERN stack development.
The following skills you must look for while hiring a freelance MERN stack developer –
- Variables and scoping
- Arrays and object
- Array methods
- Functions and arrow functions
- DOM Manipulation and event handler
- The “this” keyword
- The “class” keyword
- Prototype chain and object creation
- Higher order functions and callback functions
Well conversant with JS build tools
Highly Experienced in Testing Framework and Tool
Web application developer with the MERN stack must know about Jest, Enzyme, Mocha, Chai and AVA for unit testing. For end-to-end testing, they need to know Selenium and Webdriver in addition to Cucumber.js or Cypress. For integration tests they should use Karma among others like Nightwatch.js or Puppeteer
Hire MERN developers with Experience of Version Control Systems (VCS)
Freelance Hire MERN Developers must know about version control systems like Git, TFS, SVN and Mercurial. Git is the most commonly used one. It helps in collaborating and organizing code to maintain frequent changes that occur in the code by adding new features on feedback received from users. Along with this a developer would need to be well versed with commands such as Add, Pushing, Pulling, Committing etc., which allows them to work independently on codes while providing updates (to branches) periodically or mutually depending upon their needs/requirements at that point of time.
Familiarity with Styled Components
Knowledge of NodeJS and ExpressJS
The freelance MERN developers must have experience of using ExpressJS library in their application. ExpressJS makes easier for the developers to write concise code and customize an application. Express provide the HTTP methods GET, PUT, POST, DELETE, SET, etc. , methods to specify the template engine being used, location of template files, and which template is used for rendering a response. It helps creating router handler to provide routing for the application, handle validation and 404 errors which may occur in a MERN application.
Experience with web markup and UI, UX Concepts
The MERN stack developer must have a firm understanding of element positioning, displaying the elements, and making components interactive, semantic markup, and other related UX Concepts so they can design the product with the best quality. The developer must be experienced in developing visual effects in presentational markup. For, example – How the heading appears, making text larger and putting weight to it, and giving which color to it, and which markup can include captions, bind columns, and row headings to table cells.
Experience working with ReactJS workflows
State Management in React.js library framework is the biggest challenge developers face while developing scalable and robust MERN applications. Look for the developers who have worked with projects where they have managed states across multiple components and optimized application performance.
Check if they have worked with the popular libraries like Redux, Mobx, and Context APIs.
Proficient using MongoDB NoSQL datababase
MongoDB is gaining popularity now-a-days because of its great alignment with front-end frameworks like React.js, Vue.js and Angular.js. It is document database that stores data in BSON (binary representation of JSON) format. MongoDB does not need pre-defined schemas and can store heterogeneous types of data. It allows MERN freelancers to create multiple fields in a document. MongoDB is a powerful querying tool because any document field can be indexed and provides faster data access by using internal memory for storing data.
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MERN stands for MongoDB, ExpressJS, ReactJS, and NodeJS and is an excellent choice for developing full-stack web applications. MERN stack quickly handles front-end and back-end using high-performance React.js for the front-end which reduces the application’s load-time and Node.js on the backend handling requests asynchronously and MongoDB as the database. But, recruiting the best MERN freelance developers who are well-conversant with these combined technologies is not an easy task when a large number of freelance MERN developers are competing to grab the job opportunities. So, here UltraGenius comes to assist you in hiring only the top 1% MERN developers among 20000 developers who have applied on our platform.
Top Interview Questions to ask while hiring a freelance MERN developer
The lifecycle of the component consists of four phases -
- Initialization - The constructor() method is called before anything else when the component is initiated and sets up the initial state and other initial values. This method is called when your component is created but is not added to the DOM. Its main use is to initialize the state and bind this for component methods.
- Mounting - The component is added to the React DOM. Mounting includes the following methods like constructor(), getDerivedStateFromProps(), render(), and componentDidMount().
- Updating - The component receives changed props or states and is called when the components is re-rendered. Updating the component includes shouldComponentUpdate (), componentWillUpdate (), componentDidUpdate () methods.
- Unmounting - The component is removed from the React DOM. It includes the method componentWillUnmount().
The virtual DOM is a programming concept where a virtual representation of UI is kept in memory and synced with the real DOM with the help of a library like ReactDOM. This process is called "Reconciliation".
Whenever any data is changed in UI, the changes are rendered in Virtual DOM first, then Virtual DOM is compared with Real DOM, the Real DOM will be updated only with the things that have been changed.
Props stand for Properties in React. Props are the read-only components generally used to render dynamically generated data. Props are passed in the functions as similar as the arguments are passed. Props are always sent from parent to child component and never vice-versa.
- Props are immutable while the States are mutable.
- Props allow you to pass information from one component to another in the argument form, while a State doesn't pass but holds the information about the components.
- Props make a component reusable by passing it to the child component while States do not have any functionality like this.
- Props are external and are controlled by whatever renders the component while the State is internal and is controlled by the React Component itself.
- Props are used to communicate between the components, States can be used for rendering dynamic changes with the component.
Express.js is a robust framework of Node.js designed to minimize the lines of code while developing web applications by providing powerful set of libraries and tools which makes the development process faster and increases its scalability.
Routing specifies the way a server responds to a client's request to a particular endpoint. AN endpoint is a path and any of the HTTP methods such as GET, PUT, POST, PATCH, etc. Each route possesses one or more handler functions that gets executed when the router is matched. The syntax usually used for routing is -
app.METHOD(PATH,HANDLER), where METHOD can be any HTTP request methods like GET, PUT, POST, DELETE, SET, OPTIONS, HEAD, and CONNECT.
To work with MongoDB, the required library is mongoose. The required steps for establishing database connectivity are -
- Connection Pooling – Specify the number of database connections that should be maintained and saved by Node.js.
- Create the connection to a database. Create a callback function that can be invoked whenever the “create” method is executed.
- To retrieve and manipulate data, execute queries from the database with the help of commands such as SELECT, UPDATE, INSERT, and DELETE.
- Close the connection and create a callback function that can be invoked whenever the “close” method is executed.
Replication in MongoDB is a mechanism of creating the copy of data on multiple servers. It increases the data durability by ensuring that the data is written on multiple machines. In MongoDB, it is achieved by using replica sets. A replica set is a group of mongod objects / instances that maintains the same set of data. There are various data bearing nodes and one arbiter node which is optional. Only one of the data bearing nodes is treated as the primary node that receives all the write operations. The primary nodes stores all the changes occurred to its data sets in the operation log (oplog).
REST API is an Application Programming Interface that uses HTTP requests to GET, PUT, POST, DELETE the data over www. The developers you are hiring should be well versed with the principles of REST –
- Stateless –
The client sends the requests to the server containing all the necessary data to be dealt with. The data can be a query-string parameter, a part of URI, context body, and headers also. The URI uniquely identifies the resource and the body contains the information about the requesting resource’s state.
- Client and Server –
REST provides a uniform interface that separates the client from the server and helps in improving the UI portability across various platforms they use. It also increases the scalability of the server components.
- Uniform Interface
REST API ensures uniformity throughout the application by defining four interface constraints – Resource Identification, Resource Manipulation, Self-descriptive messages, Hypermedia.
- Layered System
REST provides a layered system architecture that limits the component behavior thereby ensuring stability. Layered system enables load balancing and enhances scalability by providing shared caches. It also helps in increasing the application’s security because components in each layer cannot communicate with the next immediate layer.
REST allows the client to download the applets and extend them via the interface to use in their applications.
Node.js uses asynchronous callbacks which are called at the completion of a given task. Asynchronous Callbacks are specified as function arguments while invoking a function which will start executing code in the background. When the background code stops running, async callbacks call the callback function to let the developers know about task completion.
A callback hell occurs when the freelance MERN developer resolves callback which is another callback which is yet in another callback. Using comments, splitting the large functions into smaller functions, using async / wait, and using promises can help preventing callback hell to occur.
The developers can maintain separate blocks for piles of code and avoid writing code in deep nested structures.
For achieving transaction and locking, developers use the concept of nesting the documents which are also known as embedded or sub document. MongoDB achieves locking by using reader-writer locks which provides concurrent readers the facility to access a shared collection or database. For example, when locking is made on a collection (using X mode), then its corresponding lock and the global lock should be locked in the intent exclusive IX mode.
Frequently Asked Questions
UltraGenius is one of the leading platforms for hiring remote talent and connecting freelance and part-time developers with Silicon Valley businesses. We focus on finding the best talents who will perform extremely well and will be easily integrated into your teams. We filter out only the top 1% most skilled freelance developers among the 20K+ developers who have applied on our platform. Candidates have to prove their self-reported experience by giving UltraGenius’ s skill tests.
UltraGenius first tests the developer’s skill set by conducting a two and half hour hiring test. Our hiring test judges a candidate on all aspects like aptitude, case study analysis, verbal and reasoning, coding questions based on data structures and algorithms, software engineering, system design, and more. Then, there is another round for the candidates who are selected from this round called “Higher-level Assessment Skill Test”, which is a video round that deeply analyzes freelance developers’ major skills and asks questions about the projects they have worked upon.
Fill up the form which is on every hiring freelancers’ page and we will inform you once we select the top 1% freelance MERN developers matching your job requirements. After analyzing the candidates based on their resumes and two assessment tests, we provide you the feedback quickly. And if the freelancers selected by our team are fit for your job role, then we also provide the onboarding.
UltraGenius offers you only the most skilled freelance developers who are top 1% among the 20K+ freelance developers who have applied on our platform. After a rigorous selection and testing process, we sort out only the top candidates for you. You can check out UltraGenius’ s selection process for hiring freelance MERN developers on https://www.ultragenius.club/hire-mern-freelancer/.