在commentList.js中：

<ul?className="list-group?mb-3">???????????????{comments.map((comment,index)=>???????????????	<li?key={index}?className="list-group-item">{comment}		<button??onClick={?(e)=>?this.props.onDeleteComment(e)}>X</button>???????????????	</li>??????????????????????)}????????????</ul>

APP.js中：

<CommentList?comments={this.state.comments}?onDeleteComment={this.state.comments.deleteComment}/>

?deleteComment(index)?{????let?newComments?=?this.state.comments????newComments.splice(index,?1)????this.setState({??????comments:?newComments????})??}

這個刪除按鈕如何做呢？每次點擊刪除就會顯示props undefined