React-native 中接收通知的问题

Question

我在反应本机博览会推送通知时遇到问题 我的应用程序的主要目标是从谷歌工作表文件中获取数据并显示它 在此代码中，我有 fetch 方法，每 20 秒检查一次添加的新项目是否更新数据

  const fetchData = async () => {
    setIsFetching(true); 
    try {
      const data = await FetchData();
      setValue(data);

      const newLength = data.length; 
      let hasNewItems = false; 

      if (data && newLength > prevLengthRef.current) {
        console.log("New Order Received:",newLength - prevLengthRef.current,"new items added");
        await sendNotification(expoPushToken);
        hasNewItems = true; // Set flag if new items found
        setInitialLength(newLength);
        prevLengthRef.current = newLength;
      } else {
        console.log("No new orders received.");
      }
      // }
    } catch (error) {
      console.error("Error:", error.message);
    } 

在此代码中，它每 20 秒执行一次该函数

  fetchData(); // Initial fetch

  const intervalId = setInterval(fetchData, 20000); // Fetch data every 20 seconds

  return () => clearInterval(intervalId);
}, []); 

这是发送通知的功能

  const sendNotification = async () => {
    try {
      console.log("Sending push notification...");
      // notification message
      const message = {
        to: expoPushToken,
        sound: "default",
        title: "New Order ",
        body: "Open the app new order received 🚀",
      };

      await fetch("https://exp.host/--/api/v2/push/send", {
        method: "POST",
        headers: {
          host: "exp.host",
          accept: "application/json",
          "accept-encoding": "gzip, deflate",
          "content-type": "application/json",
        },
        body: JSON.stringify(message),
      });
      console.log("Notification sent successfully!");
    } catch (error) {
      console.error("Error sending notification:", error);
      Alert.alert("Error", "Failed to send notification");
    }
  };

当我将函数放入按钮中时它就起作用了

<Button title="Send push notification" onPress={sendNotification} />

Answer 1

空的依赖数组意味着效果不依赖于组件范围中的任何值。因此，它应该只在初始渲染后运行一次，而不是在任何后续渲染中运行。