Question

我试图制作一个onClick事件并显示信息。

当我执行console.log以显示filteredSreen [0]时，我得到了一个对象（{id: "2", screen: "2", layer: "5", time: "13:15", dimension: "2D"}）。

当我想要访问ID或屏幕时，我在第6行做了console.log(filteredSreen[0].id)或console.log(filteredSreen[0].screen)。

他们都犯同样的错误Cannot read property 'id' of undefined或Cannot read property 'screen' of undefined

我该如何访问财产？

================================================

screeninfo是数组。

[{id: "1", screen: "2", layer: "5", time: "13:15", dimension: "2D"},{id: "2", screen: "2", layer: "5", time: "13:15", dimension: "2D"},{id: "3", screen: "2", layer: "5", time: "13:15", dimension: "2D"}]

将其保存在reduex存储中，并将其传递给BookInfo组件我发现screeninfo是使用console.log正确传递的。
并且我还使用console.log检查了{id：“ 2”，screen：“ 2”，layer：“ 5”，time：“ 13:15”，维度：“ 2D”，}的结果。但是我无法使用属性。
我临时做出这样的事情，我得到了正确的事情。

// temporary way
const filterScreen = () => {
    let filteredSreen = screeninfo.filter((item) => item.id === screenId);
    let result = filteredSreen[0];
    let screen = "";
    let layer = "";
    for (let key in result) {
      if (key === "screen") {
        screen = result[key];
      }
      if ((key = "layer")) {
        layer = result[key];
      }
    }
    return screen,layer;
  }

const BookInfo = ({ movie, theater, screenId, date, screeninfo }) => {
  const filterScreen = () => {
    let filteredSreen = screeninfo.filter((item) => item.id === screenId);
    let result = filteredSreen[0];
    console.log(result); // {id: "2", screen: "2", layer: "5", time: "13:15", dimension: "2D",}  <=line5
    console.log(result.id) // error
  };

  return (
    <div className="bookInfo">
      <div>{movie}</div>
      <div>{theater}</div>
      <div>{filterScreen()}</div>
    </div>
  );
};

Answer 1

请添加条件

  const filterScreen = () => {
    let filteredSreen = screeninfo.filter((item) => item.id === screenId);
    let result = filteredSreen[0];
    if (result && result.id) { // condition 
       console.log(result);
       console.log(result.id);
    }
  };

Answer 2

const BookInfo = ({ movie, theater, screenId, date, screeninfo }) => {
  const filterScreen = () => {
    let filteredSreen = screeninfo.filter((item) => item.id === screenId);
    let result = filteredSreen.length!==0 ? filteredSreen[0] :void 0 ;
    console.log(result); // {id: "2", screen: "2", layer: "5", time: "13:15", dimension: "2D",}  <=line5
    console.log(result.id) // error
  };

  return (
    <div className="bookInfo">
      <div>{movie}</div>
      <div>{theater}</div>
      <div>{filterScreen()}</div>
    </div>
  );
};

实际上，每次过滤条件时，您过滤的条件都不正确

无法访问React中的对象属性

2 个答案: