javascript - 如何连接对象是useState数组？

Question

我有 useState 变量。我想用新对象连接值。

const [dates,setDates] = useState(["Mon","Sun"])

规则:1.如果日期存在带有 isSelected 标志则设为 false

[{day:"mon",isSelected:false}]

否则，做为，

[{day:"mon",isSelected:true}]

下面是我的函数，

const handleDay = (day) => {
  setDates((x) => {
    x.map((v) => {
      if (day === v.day && v.isSelected) {
        v.isSelected = true;
        return {
          v,
        };
      } else {
        return {
          day,
          isSelected: true,
        };
      }
    });
  });
};

handleDay('mon');

预期输出

[{day:"mon",isSelected:true}, 'Sun']

但是我明白了，

 [{
    "day": "Mon",
    "isSelected": true
 }, {
    "day": "Mon",
    "isSelected": true
 }]

Answer 1

用这个替换你的 map 代码

arr.map(v => {
  if (day === v.day || day === v) {
    return {
      day: v.day ? v.day : v,
      isSelected: !v.isSelected
    };
  } else {
    return v
  }
});

let arr = ["Mon", "Sun"]

const handleDay = day => {
  let arr2 =  
    arr.map(v => {
      if (day === v.day || day === v) {
        return {
          day: v.day ? v.day : v,
          isSelected: !v.isSelected
        };
      } else {
        return v
      }
    });
    
    return arr2;
};

console.log(handleDay('Mon'));
arr = handleDay('Mon');
console.log(handleDay('Mon'));