Category: ReactJS Interview Question

• getInitialState(): This is executed before the creation of the component.
• componentDidMount(): Is executed when the component gets rendered and placed on the DOM.
• shouldComponentUpdate(): Is invoked when a component determines changes to the DOM and returns a “true” or “false” value based on certain conditions.
• componentDidUpdate(): Is invoked immediately after rendering takes place.
• componentWillUnmount(): Is invoked immediately before a component is destroyed and unmounted permanently.

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ReactJS Redux Interview Questions

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• Class components example:

• Functional components example:

We can embed two or more components into one using this method:

A higher-order component acts as a container for other components. This helps to keep components simple and enables re-usability. They are generally used when multiple components have to use a common logic. 

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• Props are short for Properties. It is a React built-in object that stores the value of attributes of a tag and works similarly to HTML attributes.
• Props provide a way to pass data from one component to another component. Props are passed to the component in the same way as arguments are passed in a function.

We can update the state of a component by using the built-in ‘setState()’ method:

• The state is a built-in React object that is used to contain data or information about the component. The state in a component can change over time, and whenever it changes, the component re-renders.
• The change in state can happen as a response to user action or system-generated events. It determines the behavior of the component and how it will render.