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how many time normally component render in reactjs

In ReactJS, the number of times a component renders depends on various factors, including the component's state changes, updates to its props, and changes in the parent component's state or props. The goal of React's rendering process is to efficiently update the user interface and avoid unnecessary re-renders.

Here are some key points to consider regarding how many times a component typically renders:

  1. Initial Render: When a component is first mounted (added to the DOM), it undergoes an initial render. This happens only once during the component's lifecycle.

  2. State Changes: When the component's state changes due to calls to setState or state-setting hooks (e.g., useState, useReducer), React triggers a re-render to update the UI with the new state.

  3. Prop Changes: If a parent component passes new props to a child component, the child component may re-render to reflect the changes in its UI. However, React performs a diffing algorithm to optimize rendering, and it will only update the parts of the UI that have changed.

  4. Parent Component Re-renders: If a parent component re-renders (due to its own state or prop changes), all its child components will also re-render, even if their own props or state haven't changed. This is because React re-renders the entire component tree.

  5. Use of React.memo: Components can use the React.memo higher-order component or the useMemo hook to memoize their output and prevent unnecessary re-renders when their props or state haven't changed.

  6. Rendering Optimization: React employs various optimization techniques, such as virtual DOM and reconciliation algorithms, to minimize the number of actual DOM updates and re-renders.

In general, React aims to minimize re-renders by performing a virtual DOM comparison between the previous and current component states. This comparison helps identify which parts of the DOM need updating and optimizes rendering to avoid excessive DOM manipulations.

It's important to note that the exact number of renders can vary based on the complexity of the component's UI, its usage of state and props, and how the component's parent components interact with it. Developers can further optimize rendering by using React's built-in optimizations and adopting best practices for managing state and props effectively.

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