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How to update nested state properties in React?

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In React, when wwe need to update nested state properties, we should avoid mutating the state directly due to React’s immutability principle. Instead, we should create a new object that represents the updated state. Here’s how we can update nested state properties:

Let’s say we have a state object like this:

state = {
  nestedObject: {
    nestedProperty: 'value'
  }
};

To update nestedProperty, we would typically do something like this:

// Create a new object representing the updated state
const updatedState = {
  ...this.state,
  nestedObject: {
    ...this.state.nestedObject,
    nestedProperty: 'new value'
  }
};

// Update the state with the new object
this.setState({ nestedObject: updatedState });

This approach ensures that we are not mutating the original state object. We’re creating a new object by spreading the existing state and then spreading the nested object we want to update, along with the specific property we want to change.

Another approach, if we are using functional updates with setState, would look like this:

this.setState(prevState => ({
  nestedObject: {
    ...prevState.nestedObject,
    nestedProperty: 'new value'
  }
}));

Here, prevState represents the previous state. We’re returning a new object with the updated nested property while preserving the rest of the state.

These methods ensure that we follow React’s immutability principle, which helps prevent potential bugs and makes it easier to reason about state changes in our application.

By John Au-Yeung

Web developer specializing in React, Vue, and front end development.

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