Syntax error : JSON parse error : unrecognixed token '<'

Question

Syntax error : JSON parse error : unrecognixed token '<' find solution of this error. one page is working a fine with same code and one page shown this error with same code. i did not understand what is my mistake.

fron end code

const getdata = async () => {

try {
  const res = await fetch(`http://192.168.43.220:8000/getuser/${id}`, {
    method: "GET",
    headers: {
      "Content-Type": "application/json"
    },
  })

  const data = await res.json();
  console.log(data.costomer);
  if (!data) {
    window.alert('error in get data')
  }
  else {
    setdata(data.costomer)
    console.log('data goted by api');
  }

} catch (e) {
  console.log(e);
  window.alert(e)
  window.alert("failed")
}
}

and this is back end code

app.get('/getuser/:id', async (req, res) => {
try {
    const { id } = req.params
    console.log(id);
    const peruserdata = await getschema.findById(id);
    res.status(201).json(peruserdata);
} catch (error) {
    res.send(error)
}

})

that error usually indicates that the server is replying with HTML - check the browser developer tools to see exactly what the server is sending in the response — Jaromanda X
– Jaromanda X, Commented Sep 9, 2022 at 2:50
or change the data variable to const data = await res.text(); and then you can see what is returned. — Steve
– Steve, Commented Sep 9, 2022 at 3:53
Does this answer your question? JSON Parse error: Unrecognized token'<' - react-native — AD7six
– AD7six, Commented Sep 9, 2022 at 4:23

enlightenment support family · Accepted Answer · 2022-09-09 03:12:33Z

0

Whether the error occurred at the front end or the back end. It is recommended that you try debugging the data results returned by the back end

answered Sep 9, 2022 at 3:12

enlightenment support family

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1 Comment

Dykotomee Over a year ago

This looks like a comment and not an answer. If you have a question for the original poster, you should leave a comment in the question's thread instead of submitting an answer. Answers should be submitted when you feel you can reasonably solve the original poster's question.

yizzzz · Accepted Answer · 2022-09-09 04:20:33Z

0

The error is from this code:

const data = await res.json();

You're implying that the res can be parsed as JSON but it isn't. What you can do is check the expected HTTP status of the request first before parsing the response.

const res = await fetch(...)
if (res.status !== 201) {
    // error handling
}

// parse it here now
const jsonResponse = await res.json()

answered Sep 9, 2022 at 4:20

yizzzz

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