如果有人正在搜索useState()钩子，则更新为对象

- Through Input

        const [state, setState] = useState({ fName: "", lName: "" });
        const handleChange = e => {
            const { name, value } = e.target;
            setState(prevState => ({
                ...prevState,
                [name]: value
            }));
        };

        <input
            value={state.fName}
            type="text"
            onChange={handleChange}
            name="fName"
        />
        <input
            value={state.lName}
            type="text"
            onChange={handleChange}
            name="lName"
        />
   ***************************

 - Through onSubmit or button click
    
        setState(prevState => ({
            ...prevState,
            fName: 'your updated value here'
         }));

function App() {

  const [todos, setTodos] = useState([
    { id: 1, title: "Selectus aut autem", completed: false },
    { id: 2, title: "Luis ut nam facilis et officia qui", completed: false },
    { id: 3, title: "Fugiat veniam minus", completed: false },
    { id: 4, title: "Aet porro tempora", completed: true },
    { id: 5, title: "Laboriosam mollitia et enim quasi", completed: false }
  ]);

  const changeInput = (e) => {todos.map(items => items.id === parseInt(e.target.value) && (items.completed = e.target.checked));
 setTodos([...todos], todos);}
  return (
    <div className="container">
      {todos.map(items => {
        return (
          <div key={items.id}>
            <label>
<input type="checkbox" 
onChange={changeInput} 
value={items.id} 
checked={items.completed} />&nbsp; {items.title}</label>
          </div>
        )
      })}
    </div>
  );
}

2022年

如果您正在寻找与此相同的功能。函数组件中的setState(来自类组件)，那么这是对您有很大帮助的答案。

例如

你有一个像下面这样的状态，想要从整个状态中更新特定的字段，那么你需要每次都使用对象解构，有时它会令人恼火。

const [state, setState] = useState({first: 1, second: 2});

// results will be state = {first: 3} instead of {first: 3, second: 2}
setState({first: 3})

// To resolve that you need to use object destructing every time
// results will be state = {first: 3, second: 2}
setState(prev => ({...prev, first: 3}))

为了解决这个问题，我提出了useReducer方法。请检查useReducer。

const stateReducer = (state, action) => ({
  ...state,
  ...(typeof action === 'function' ? action(state) : action),
});

const [state, setState] = useReducer(stateReducer, {first: 1, second: 2});

// results will be state = {first: 3, second: 2}
setState({first: 3})

// you can also access the previous state callback if you want
// results will remain same, state = {first: 3, second: 2}
setState(prev => ({...prev, first: 3}))

您可以将该stateReducer存储在utils文件中，如果需要，也可以将其导入到每个文件中。

如果你需要，这里是自定义钩子。

import React from 'react';

export const stateReducer = (state, action) => ({
  ...state,
  ...(typeof action === 'function' ? action(state) : action),
});

const useReducer = (initial, lazyInitializer = null) => {
  const [state, setState] = React.useReducer(stateReducer, initial, init =>
    lazyInitializer ? lazyInitializer(init) : init
  );

  return [state, setState];
};

export default useReducer;

打印稿

import React, { Dispatch } from "react";

type SetStateAction<S> = S | ((prev: S) => S);

type STATE<R> = [R, Dispatch<SetStateAction<Partial<R>>>];

const stateReducer = (state, action) => ({
  ...state,
  ...(typeof action === "function" ? action(state) : action),
});

const useReducer = <S>(initial, lazyInitializer = null): STATE<S> => {
  const [state, setState] = React.useReducer(stateReducer, initial, (init) =>
    lazyInitializer ? lazyInitializer(init) : init,
  );

  return [state, setState];
};

export default useReducer;

我认为最好的解决办法是Immer。它允许你像直接修改字段一样更新对象(masterField.fieldOne。Fieldx = 'abc')。但它当然不会改变实际对象。它收集草稿对象上的所有更新，并在最后为您提供一个最终对象，您可以使用它来替换原始对象。

如果你使用布尔值和数组，这可以帮助你:

const [checkedOrders, setCheckedOrders] = useState<Record<string, TEntity>>({});

const handleToggleCheck = (entity: TEntity) => {
  const _checkedOrders = { ...checkedOrders };
  const isChecked = entity.id in checkedOrders;

  if (isChecked) {
    delete _checkedOrders[entity.id];
  } else {
    _checkedOrders[entity.id] = entity;
  }

  setCheckedOrders(_checkedOrders);
};

最初我在useState中使用object，但后来我移动到useReducer钩子用于复杂的情况。重构代码时，我感到性能有所提高。

当您有涉及多个子值的复杂状态逻辑时，或者当下一个状态依赖于前一个状态时，useReducer通常比useState更可取。

useReducer React文档

我已经实现了这样的钩子供我自己使用:

/**
 * Same as useObjectState but uses useReducer instead of useState
 *  (better performance for complex cases)
 * @param {*} PropsWithDefaultValues object with all needed props 
 * and their initial value
 * @returns [state, setProp] state - the state object, setProp - dispatch 
 * changes one (given prop name & prop value) or multiple props (given an 
 * object { prop: value, ...}) in object state
 */
export function useObjectReducer(PropsWithDefaultValues) {
  const [state, dispatch] = useReducer(reducer, PropsWithDefaultValues);

  //newFieldsVal={[field_name]: [field_value], ...}
  function reducer(state, newFieldsVal) {
    return { ...state, ...newFieldsVal };
  }

  return [
    state,
    (newFieldsVal, newVal) => {
      if (typeof newVal !== "undefined") {
        const tmp = {};
        tmp[newFieldsVal] = newVal;
        dispatch(tmp);
      } else {
        dispatch(newFieldsVal);
      }
    },
  ];
}

更多相关的钩子。