React Interview Questions and Answers
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Ques 36. What would you do if your React application is rendering slowly?
The cause of slow rendering in React is mostly because of the number of re-render operations, which are sometimes unnecessary. There are two main tools provided by React to help users here:
- memo(): This is used to prevent all of the unnecessary re-rendering carried out by the function components.
- PureComponent: This is used to ensure that the unnecessary re-rendering of class components is avoided.
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Ques 37. Can you conditionally add attributes to components in React?
Yes, there is a way in which you can add attributes to a React component when certain conditions are met.
React has the ability to omit an attribute if the value passed to it is not true.
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Ques 38. Why is props passed to the super() function in React?
Props gets passed onto the super() function if a user wishes to access this.props in the constructor.
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Ques 39. What are the predefined prop types present in React?
There are five main predefined prop types in React. They are as follows:
- PropTypes.bool
- PropTypes.func
- PropTypes.node
- PropTypes.number
- PropTypes.string
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Ques 40. What is the difference between Virtual DOM and Real DOM?
Virtual DOM | Real DOM |
Changes can be made easily | Changes can be expensive |
Minimal memory wastage | High demand for memory and more wastage |
JSX element is updated if the element exists | Creates a new DOM every time an element gets updated |
Cannot update HTML directly | Able to directly manipulate HTML |
Faster updates | Slow updates |
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