arrays - 如何在不删除旧状态的情况下设置对象的状态数组

Question

如何在不清除初始状态的情况下设置单个数组中的对象数组。

const [arr,setArr]=useState([])

const arr1=[{key:'a',value:'a'},{key:'b',value:'b'}]
const arr2=[{key:'c',value:'c'},{key:'d',value:'d'}]

1st cycle setState
setArr((prevState)=>(prevState.push(...arr1)) // required state  arr=[{key:'a',value:'a'},{key:'b',value:'b'}]

2st cycle setState
setArr((prevState)=>(prevState.push(...arr2)) //  required state arr=[{key:'a',value:'a'},{key:'b',value:'b'},{key:'c',value:'c'},{key:'d',value:'d'}]

Answer 1

Array#push返回新数组的 length。尝试使用 spread operator相反:

setArr((prevState) => [...prevState, ...arr1]);
setArr((prevState) => [...prevState, ...arr2]);