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To update an object state array in React:

1. Use map()the method to iterate over an array.
2. In each iteration, check whether a condition is met.
3. Updates the properties of objects that match the criteria.

import {useState} from 'react';

export default function App() {
  const initialState = [
    {id: 1, name: 'Jiyik', country: 'China'},
    {id: 2, name: 'Bob', country: 'Belgium'},
  ];

  const [employees, setEmployees] = useState(initialState);

  // ✅ 将对象添加到状态数组
  const addObjectToArray = obj => {
    setEmployees(current => [...current, obj]);
  };

  // ✅ 更新状态数组中的一个或多个对象
  const updateObjectInArray = () => {
    setEmployees(current =>
      current.map(obj => {
        if (obj.id === 2) {
          return {...obj, name: 'Sophia', country: 'Sweden'};
        }

        return obj;
      }),
    );
  };

  // ✅ 从状态数组中移除一个或多个对象
  const removeObjectFromArray = () => {
    setEmployees(current =>
      current.filter(obj => {
        return obj.id !== 2;
      }),
    );
  };

  return (
    <div>
      <button
        onClick={() =>
          addObjectToArray({
            id: Math.random(),
            name: 'Carl',
            country: 'Canada',
          })
        }
      >
        Add employee
      </button>

      <button onClick={updateObjectInArray}>Update object in array</button>

      <button onClick={removeObjectFromArray}>Remove object from array</button>

      {employees.map(employee => {
        return (
          <div key={employee.id}>
            <h2>name: {employee.name}</h2>
            <h2>country: {employee.country}</h2>

            <hr />
          </div>
        );
      })}
    </div>
  );
}

These examples show how to:

1. Add an object to the state array.
2. Updates one or more objects in the state array.
3. Removes one or more objects from the state array.

To add an object to the state array, we have to use the spread syntax ...to unpack the elements of the array and add the object at the end.

const addObjectToArray = obj => {
  setEmployees(current => [...current, obj]);
};

addObjectToArray({
  id: 3,
  name: 'Carl',
  country: 'Canada',
})

We setStatepass a function to , because it is guaranteed to be called with the current (latest) state.

To update objects in the state array, call map()the method to iterate the array and update the objects that match the criteria.

const updateObjectInArray = () => {
  setEmployees(current =>
    current.map(obj => {
      if (obj.id === 2) {
        return {...obj, name: 'Sophia', country: 'Sweden'};
      }

      return obj;
    }),
  );
};

The function we pass to Array.mapthe method is called for each element in the array.

In each iteration, we check if the object's id is equal to 2, and if so, we update its name and country attributes.

Otherwise, we return the object as is.

We can Array.filterremove an object from the state array in React using the remove method.

const removeObjectFromArray = () => {
  setEmployees(current =>
    current.filter(obj => {
      return obj.id !== 2;
    }),
  );
};

The function we pass to filterthe method is called for each element in the array.

In each iteration, we check if the object's id is not equal to 2 and return the result.

filterThe method returns a new array containing only the true values ​​returned by the callback function.