Quadb Tech Mern Full Stack Developer Interview Questions and Answers

Q1. What is differnce between class and functional component
Ans. 
Class components are ES6 classes that extend from React.Component and have a render method, while functional components are simple functions that return JSX.
• Class components are more feature-rich and have access to lifecycle methods like componentDidMount, componentDidUpdate, etc.

• Functional components are simpler and easier to read, especially for simple UI components.

• Functional components can use React Hooks to manage...read more
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Q2. Write a basic function component
Ans. 
A basic function component in React
• Create a function component using the 'function' keyword

• Return JSX elements within the component function

• Example: const MyComponent = () => { return

  Hello World!
  ; }
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Q1. What is virtual DOM?
Ans. 
Virtual DOM is a lightweight copy of the actual DOM that allows for efficient updates and rendering in web applications.
• Virtual DOM is a concept used in frameworks like React to improve performance by minimizing direct manipulation of the actual DOM.

• When changes are made to the virtual DOM, a comparison is done with the actual DOM to identify the minimal number of updates needed.

• This approach reduces the number of DOM ...read more
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Q2. What is foriegn Key SQL?
Ans. 
Foreign key in SQL is a field in a table that is a primary key in another table, establishing a relationship between the two tables.
• A foreign key constraint ensures referential integrity between two related tables.

• It helps maintain consistency and avoid orphan records.

• Example: In a database with tables 'orders' and 'customers', the 'customer_id' in 'orders' table can be a foreign key referencing the 'id' column in 'cus
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Q1. What is props
Ans. 
Props are read-only properties that are 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 changed by the child component.

• Props are accessed in the child component using this.props.
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Q2. What is Good feedback you ever got in during you development period.
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Q1. What is error handling middleware?
Ans. 
Error handling middleware is a function that processes errors in an Express application.
• Error handling middleware is defined with four parameters: err, req, res, and next.

• It is used to catch errors that occur during the execution of route handlers or other middleware functions.

• It is typically defined at the end of the middleware chain with app.use() and has a signature like (err, req, res, next) => {...}.

• Example: app.u...read more
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Good one hour arrays linbklist strings

Q1. Which one you choose mongo vs mysql and why
Ans. 
I would choose MongoDB for its flexibility and scalability in handling unstructured data.
• MongoDB is a NoSQL database, making it easier to work with unstructured data compared to MySQL which is a relational database.

• MongoDB is highly scalable and can handle large amounts of data and high traffic loads.

• MongoDB is a good choice for applications that require frequent updates and real-time analytics.

• MySQL is a better choice...read more
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Oops,Function ,and basic concept of cloud

Q1. Tell me about your self. Why are you interested in this company/role?
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Q2. Do you have any questions for us
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Q3. Greatest professional achievement so far
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Q4. Short team and long team goals
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Q5. Your strength & weakness
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Q1. Was asking in-depth about my past company's projects
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Q2. Was asking in-depth in my technology which i mentioned in resume
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