Bolt IoT Front end Developer Interview Questions and Answers

Q1. Hoisting concept with examples and guess the output
Add your answer
Q2. Map functionality with a call back function
Add your answer
Q3. Copy object, spread operator usage . Deep copy, sallow copy
Add your answer
Q4. Flexbox vs grid, dom, box model,
Add your answer
Q5. React optimization, why React,
Add your answer

Q1. Mostly js questions, not so many of angular or react.
Add your answer
Q2. Like fizbuzz or things like that.
Add your answer

Coding a frontend UI from provided image. And creating a fucntional star rating system

Q1. Designing a Component API in React using Typescript.
Ans. 
Designing a Component API in React using Typescript involves defining props, state, and methods for the component.
• Define the props interface to specify the expected input data for the component

• Use typescript types to ensure type safety and prevent runtime errors

• Define the state interface to manage the internal state of the component

• Implement methods to handle user interactions and component logic

• Document the component
Answered by AI
Add your answer
Q2. Create a function that can clear all the timer ids at once.
Ans. 
Function to clear all timer ids at once
• Create an array to store all timer ids

• Iterate through the array and clear each timer id using clearTimeout() function
Answered by AI
Add your answer

Q1. Introduction life cycle looks pipe @input @output
Add your answer

Q1. What is event bubbling
Add your answer
Q2. What is TDD and why TDD
Add your answer

Reactive form and crud operations pipes crud operations

Q1. Basic understanding of js and angular is must expeciallly how js works questions on arrays objects shallow deep copy
Add your answer

Q1. Let var const in JavaScript
Ans. 
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
Answered by AI
Add your answer
Q2. Error boundary and how to handle
Ans. 
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
Answered by AI
Add your answer
Q3. Event.bind and event.property
Add your answer
Q4. Use of never in typescript
Ans. 
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
Answered by AI
Add your answer
Q5. What hooks you have used
Ans. 
I have used React hooks such as useState, useEffect, useContext, and useRef in my projects.
• useState

• useEffect

• useContext

• useRef
Answered by AI
Add your answer
Q6. What is difference between use reducer and use state
Ans. 
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
Answered by AI
Add your answer
Q7. Why we use state and props
Add your answer
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
Answered by AI
Add your answer
Q9. Write your own custom hook
Ans. 
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
Answered by AI
Add your answer
Q10. Explain map filter and reduce functions
Ans. 
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
Answered by AI
Add your answer
Q11. How you can clone an object
Ans. 
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.
Answered by AI
Add your answer
Q12. What are the three stages of event propagation and how to handle it
Ans. 
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.
Answered by AI
Add your answer
Q13. How to handle errors in your react application
Ans. 
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
Answered by AI
Add your answer
Q14. Write code to call fake api and display the title where category is “some category “
Add your answer

Q1. It was a array question. I was told to return a object from a function which would contain getting all the array elements, adding a element, deleting a element. The test was on hacker rank.
Add your answer

Q1. This was basically a one on one round. I was asked basics of HTML, CSS and React. Questions like Hoisting, Prop Drilling, Context API. Not only do you need to know what the topics are. But I was asked to i...read more
Add your answer

Q1. Basic Company Details and Salary Negotiations
Add your answer