Note for the use of react for select and similar components

<ul>
｛list.map((item,index)=><li key={
    
    index}>{
    
    item}</li>)｝
</ul>

The above is wrong writing, it is recommended not to use index as the value of key.
Because once the order of the elements in the list is changed, a large number of key failures may occur, which will cause a large number of modification operations.