1 回答顯示Cannot read property 'previousSibling' of undefined？

5 回答 Cannot read property 'replaceChild' of undefined at replaceMessage

1 回答這里實(shí)現(xiàn)背景變色的，就是這樣寫的話會提示Cannot read property 'style' of undefined，為什么？

1 回答為什么在刪除的時候會出現(xiàn) Uncaught TypeError: Cannot read property 'parentNode' of undefined

1 回答Unable to set property 'checked' of undefined or null reference報(bào)錯原因