在反应中每一秒发送请求

Question

在响应res.readyToShow ===真之前，我如何每秒钟进行一次提取请求。如果res.status为真，则停止请求。

我希望每秒钟发送一个请求，以验证readyToShow是否为真。我不能使用套接字或网络钩子。

 test = (ossUrn, md5Checksum) => setTimeout (() => {
    fetch(
      `google/isReadyToShow`,{
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
      },
      body: JSON.stringify({
        urn: ossUrn,
        md5Checksum: md5Checksum,
      }),
    })
    .then((response) => {
      response.json().then((res) => {
          console.log('response ', res);
          return (res.readyToShow)  ? 0 : this.test(ossUrn, md5Checksum);
        });
    })
      .catch((err) => {
        console.log('err ', err);
      });
  } , 2.5 * 1000);

return fetch(
          `google/translation`,
          {
            headers: {
              'X-ACCESS-TOKEN-APP' : accessTokenApp,
              'X-DRIVE-ID': e.itemData.id,
              'X-FILE-NAME': e.itemData.name,
              'X-FILE-TYPE': e.itemData.mimeType,
              'X-FILE-MD5': e.itemData.md5Checksum,
            },
          }
        )
        .then((response) => {
            console.log("google item of id clicked " + e.itemData.id);
            response.json().then((res) => {
              console.log('response ', res);
              md5Checksum = e.itemData.md5Checksum;
              ossUrn =  res.urn;
              console.log('URN ', ossUrn)
              console.log('URL', res);
              console.log('MD5', md5Checksum);
              // execute the function to check if the file is ready to be shown
              this.test(ossUrn, md5Checksum);
            })         
              .catch((err) => {
                console.log(err);
              });
        }).catch(() => { throw new Error('Data Loading Error'); });
      
    }

我尝试使用这段代码，但是我有一个错误：

TypeError: Cannot read properties of undefined (reading 'test')

Answer 1

您可以将setInterval与一个变量或状态一起使用，该变量或状态确定间隔是否应该继续，或者如果您应该调用clearInterval，因为您已经得到了所需的结果。类似于：

function myIntervalFunction() {
   fetch(/*your fetch code*/).then(res => {
      if(res.readyToShow) {
         // setState, or change a let variable to true
      }
   })
}

const myInterval = setInterval(myIntervalFunction, 1000) // executes every 1s
// if you're doing it inside a component use state, if outside use a let that starts with false
if(myState || myLetVar === true) { // got what you wanted
  clearInterval(myInterval) // stops interval
}