React key prop not must

Question

我对 PROP 键有误解 我管理一个带有删除选项的列表 我不使用 KEY（或有​​时将索引名称用作键） 尽管我预计会发生问题，但一切正常

Answer 1

The key prop is used by React internally to track a Component back to its respective virtual DOM element. This helps React do minimal component re-renders, which in turn makes your application more performant. From the React docs on keys :

Keys help React identify which items have changed, are added, or are removed. Keys should be given to the elements inside the array to give the elements a stable identity

The best way to pick a key is to use a string that uniquely identifies a list item among its siblings. Most often you would use IDs from your data as keys

The key prop is not required, but using it with a list will help to significantly reduce the number of times a Component list child is re-rendered.

TL;DR : Always use a unique key for children of a list (eg, when using map over an array to create components). It'll help React, but isn't necessary for your app to function.