如何在列表中以不同方式定位每个元素？

Question

我想以不同的方式操作每个“li”。就像有 3 个“li”，所以当我点击它相应的按钮时，只有那个应该改变，但所有三个都在改变（我能理解为什么会这样）但是有什么办法可以找到解决方案所以只有相应的列表在div中

更改

    const nextThree =[];
    for(let i=3;i<6;i++){
        nextThree.push(<div className="week-item">
            <h1>{weeks?.[i].weekday}</h1>
            <ul>
                {weeks?.[i].tasks.map(task =>{
                    return(
                        <li onClick={()=> setDone(true)} className={done?"b":""}><button></button>{task}</li>
                    );
                })}
            </ul>
        </div>);
    }

注意：我有一个包含 6 个元素的数组，它们 div 分为两个 div，每个 div 包含 3 个元素，这就是为什么我使用这样的循环

Answer 1

要设置元素的状态（例如 done），您需要跟踪状态。在带有功能组件的 React 中，您可以使用 useState 挂钩。

const { useState } = React

const Weekday = ({ weekday = '', tasks = [], handleClick }) => {
  return (
    <div>
      <h2>{weekday}</h2>
      <ul>
      {
        tasks.map(({ name = '', done = false }, idx) => {
          return (
            <li
              key={idx}
              className={`task ${done ? 'done' : ''}`}
              onClick={() => handleClick(name)}
            >{name}</li>
          )
        })
      }
      </ul>
    </div>
  )
}

const App = ({ weekly }) => {
  // for tracking state of tasks
  const [state, setState] = useState(weekly)
  
  const setDone = (weekday) => (taskName) => {
    // setting new state based on weekday & taskName
    // parameters; merging with unchanged data
    setState(prevState => {
      return prevState.map(day => {
        if (day.weekday !== weekday) {
          return day
        } else {
          return {
            ...day,
            tasks: day.tasks.map(task => {
              if (task.name !== taskName) {
                return task
              } else {
                return {
                  ...task,
                  done: !task.done,
                }
              }
            })
          }
        }
      })
    })
  }

  return (
    <div>
      {
        state.map(({ weekday, tasks }, idx) => {
          return (
            <Weekday
              key={idx}
              weekday={weekday}
              tasks={tasks}
              handleClick={setDone(weekday)}
            />
          )
        })
      }
    </div>
  )
}

const data = [
  {
    weekday: 'Monday',
    tasks: [
      {
        name: 'Monday task 1',
        done: false,
      },
      {
        name: 'Monday task 2',
        done: false,
      },
      {
        name: 'Monday task 3',
        done: false,
      },
    ]
  },
  {
    weekday: 'Tuesday',
    tasks: [
      {
        name: 'Tuesday task 1',
        done: false,
      },
      {
        name: 'Tuesday task 2',
        done: false,
      },
      {
        name: 'Tuesday task 3',
        done: false,
      },
    ]
  },
  {
    weekday: 'Wednesday',
    tasks: [
      {
        name: 'Wednesday task 1',
        done: false,
      },
      {
        name: 'Wednesday task 2',
        done: false,
      },
      {
        name: 'Wednesday task 3',
        done: false,
      },
    ]
  },
]

ReactDOM.render(
  <App weekly={data} />,
  document.getElementById('root')
);

.task {
  cursor: pointer;
}
.done {
  text-decoration: line-through;
}

<script src="https://unpkg.com/react@17/umd/react.development.js" crossorigin></script>
  <script src="https://unpkg.com/react-dom@17/umd/react-dom.development.js" crossorigin></script>
  
<div id="root"></div>

处理这些组件的状态可能有不同的解决方案 - 可能将任务状态下推到 Weekday 组件会使更新功能更简单。在这种情况下，唯一有状态的组件是 App：这样更容易更改 Weekday 组件，因为您只需要关心它接收到的道具。

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