這是因爲news在this.state = { //... }中初始化時設置爲空,後續通過axios獲得數據,在遍歷數組時要加一個空值判斷;
render() { const newsList = (this.state.news || []).map((item, index) => <p>{item}</p> ); return( <div> {newsList} </div> ) }
這是因爲news在this.state = { //... }中初始化時設置爲空,後續通過axios獲得數據,在遍歷數組時要加一個空值判斷;
render() { const newsList = (this.state.news || []).map((item, index) => <p>{item}</p> ); return( <div> {newsList} </div> ) }