SiftHub Front end Developer Interview Questions and Answers

Q1. Based on html,css Javascript
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Q2. Based on ReactJs
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Q3. Javascript promise method
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JavaScript Promise is an object representing the eventual completion or failure of an asynchronous operation.
• Promises are used to handle asynchronous operations such as fetching data from an API.

• They have three states: pending, fulfilled, or rejected.

• Promises can be chained using .then() and .catch() methods.

• Promises can also be created using the Promise constructor.
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Q4. Javascript callback funtions
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Based on html, Css, Javascript and React-Js

Q1. What is mean by dom
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DOM stands for Document Object Model, which is a programming interface for web documents.
• DOM is a representation of the structure of a web page, allowing scripts to dynamically access and update the content, structure, and style of the document.

• It provides a way for scripts to interact with the web page by accessing and manipulating elements like text, images, forms, etc.

• DOM is platform and language-independent, allowi...read more
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Q2. Explain promise in typescript
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Promises in TypeScript are objects representing the eventual completion or failure of an asynchronous operation.
• Promises are used to handle asynchronous operations in a more readable and manageable way.

• They can be in one of three states: pending, fulfilled, or rejected.

• Promises can be chained using .then() to handle success and .catch() to handle errors.

• Example: const myPromise = new Promise((resolve, reject) => { ... ...read more
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Q3. Explain hooks in javascript
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Hooks in JavaScript are functions that let you use state and other React features without writing a class.
• Hooks were introduced in React 16.8 to allow functional components to have state and lifecycle methods.

• useState() is a hook that allows you to add state to functional components.

• useEffect() is a hook that allows you to perform side effects in functional components.

• Custom hooks are functions that allow you to reuse ...read more
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Q4. Write a program 1 to 100 prime numbers
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Generate an array of prime numbers from 1 to 100.
• Iterate from 1 to 100 and check if each number is prime

• A prime number is only divisible by 1 and itself

• Start with a list of prime numbers and check divisibility
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Q1. Let var const in JavaScript
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var and const are used to declare variables in JavaScript, with var being mutable and const being immutable.
• var is used to declare variables that can be reassigned and updated

• const is used to declare variables that cannot be reassigned or updated

• let is another keyword used for declaring variables, similar to var but with block scope
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Q2. Error boundary and how to handle
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Error boundary is a React component that catches JavaScript errors anywhere in a component tree and logs those errors.
• Error boundaries are React components that catch JavaScript errors in their child component tree.

• They are used to prevent the entire UI from crashing due to a single error.

• Error boundaries work like a JavaScript catch {} block, but for components.

• They are defined using componentDidCatch lifecycle method...read more
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Q3. Event.bind and event.property
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Q4. Use of never in typescript
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The 'never' type in TypeScript represents a value that will never occur.
• Used to indicate that a function will not return a value

• Commonly used in union types to exclude certain values

• Helps catch potential errors at compile time
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Q5. What hooks you have used
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I have used React hooks such as useState, useEffect, useContext, and useRef in my projects.
• useState

• useEffect

• useContext

• useRef
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Q6. What is difference between use reducer and use state
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useReducer is preferred for managing complex state logic, while useState is simpler for basic state management.
• useReducer is more suitable for managing complex state logic and multiple state values

• useState is simpler and more straightforward for basic state management with a single value

• useReducer allows for more organized and centralized state updates through actions and reducers

• useState is commonly used for simple co...read more
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Q7. Why we use state and props
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Q8. How you will pass data from parent to child
Ans. 
Data can be passed from parent to child components in React using props.
• Pass data as props from parent component to child component

• Use state management libraries like Redux or Context API for complex data sharing

• Use callback functions to pass data from child to parent components
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Q9. Write your own custom hook
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Custom hook to fetch data from an API
• Create a function that uses the useState and useEffect hooks

• Use the fetch API to make a request to the desired endpoint

• Return the fetched data and loading state in an array
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Q10. Explain map filter and reduce functions
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Map, filter, and reduce are higher-order functions in JavaScript used to manipulate arrays.
• Map: Transforms each element in an array and returns a new array with the transformed elements.

• Example: [1, 2, 3].map(num => num * 2) returns [2, 4, 6].

• Filter: Returns a new array with elements that pass a certain condition.

• Example: [1, 2, 3].filter(num => num > 1) returns [2, 3].

• Reduce: Applies a function against an accumulator ...read more
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Q11. How you can clone an object
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To clone an object in JavaScript, you can use the spread operator or Object.assign() method.
• Use the spread operator to create a shallow copy of an object: const clonedObj = { ...originalObj };

• Use Object.assign() method to create a shallow copy of an object: const clonedObj = Object.assign({}, originalObj);

• For deep cloning, you can use libraries like Lodash or write a custom function to recursively clone nested objects.
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Q12. What are the three stages of event propagation and how to handle it
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Event propagation consists of three stages: capturing, target, and bubbling.
• Capturing phase: Events are captured from the outermost element to the target element.

• Target phase: Event reaches the target element where the event originated.

• Bubbling phase: Events bubble up from the target element to the outermost element.
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Q13. How to handle errors in your react application
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Errors in a React application can be handled by using error boundaries, try-catch blocks, and displaying error messages to users.
• Use error boundaries to catch errors in components and display a fallback UI

• Wrap code that may throw errors in try-catch blocks to handle exceptions

• Use libraries like React Error Boundary to easily implement error handling

• Display error messages to users to inform them about the issue and poss...read more
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Q14. Write code to call fake api and display the title where category is “some category “
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Q1. Basics of react and JavaScript
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