@des
@yyss8
e 确实没变 null e.target 变 null 了 后来先把 e.target 赋给 temp 是可以的，不过警告了
arning: This synthetic event is reused for performance reasons. If you're seeing this, you're accessing the property `target` on a released/nullified synthetic event. This is set to null. If you must keep the original synthetic event around, use event.persist().
查了下 如果在 react 中想异步访问事件属性（如在 setTimeout 内），应该在是处理事件时调用 event.persist()，这会从事件池中移除该合成函数并允许对该合成事件的引用被保留下来