SyntaxError: "JSON.parse: unexpected end of data at line 1 column 1 of the JSON data" on using Fetch in reactjs

Question

I am getting above mentioned error on trying to retrieve the JSON response from Fetch API. For some reason it works with 2 API's out of 4, but not for the rest 2. I do not see any difference on Front end code in retrieving the response. Please have a look into below code:

I am not sure what's incorrect here:

 async handleSubmit(event) {
    event.preventDefault();
    let responseArray = [];
    const token = localStorage.getItem("token");
    let url = "https://api_sports/api/developSports/?";
    var form = new FormData();
    form.append("destIds", this.state.destID);
    form.append("destInfo", this.state.infoID);
    form.append("destPostal", this.state.postID);

    // Figure out the way to append the data in form
    await fetch(url, {
      method: "POST",
      body: form,
      headers: { "Authorization": `Token ${token}` },
      "mimeType": "multipart/form-data",
    }).then((results) => {
      return results.json()
    }).then(response => {
      console.log("Actual Response: ", response)
      if (response.status === 204) {
        console.log("Response 204: ", response)
        this.setState({ alertMessage: "Success" })
      }
     else if (response.status === "error") {
        console.log("Expected Error : ", response);
        responseArray.push(response.messages);
        this.setState({
            alertMessage: "IPError",
            rangeArray: responseArray[0]
        });
    }
    })
    .catch(err => {
      console.log("Error ", err);
    })
  }

Thank you

Answer 1

Please check you API response once Because your API is not returning a JSON object that why you are getting this error. It may be a malformed JSON in response.

Answer 2

I was able to fix this issue by adding below code, splitting the response into two (HTTP and JSON)

await fetch(url, {
      method: "POST",
      body: form,
      headers: { "Authorization": `Token ${token}` },
      "mimeType": "multipart/form-data",
    }).then((results) => {
      if (results.status === 204) {
        this.setState({ alertMessage: "Success" })
      }
      else {
        return results.json()
          .then(response => {
            if (response.status === "error") {
              responseArray.push(response.messages);
              this.setState({
                alertMessage: "Failure",
                rangeArray: responseArray[0]
              });
            }
          });
      }
    })

Thank you everyone