React Js: Uncaught (In Promise) Syntaxerror: Unexpected Token < in JSON at Position 0

React Js: Uncaught (in promise) SyntaxError: Unexpected token in JSON at position 0

Add two headers Content-Type and Accept to be equal to application/json.

handleGetJson(){
  console.log("inside handleGetJson");
  fetch(`./fr.json`, {
      headers : { 
        'Content-Type': 'application/json',
        'Accept': 'application/json'
       }

    })
    .then((response) => response.json())
    .then((messages) => {console.log("messages");});
}

Uncaught (in promise) SyntaxError: Unexpected token in JSON at position 0 ERROR -- NodeJS, MongoDB, React Application

Express uses precedence when defining routes. I had the following code placed above all of my get routes, therefore overriding them.

app.get("*", function (request, response) {
  response.sendFile(path.resolve(__dirname, "../frontend/build", "index.html"));
});

Solution:

I moved those lines of code to the bottom so that the other routes would take precedence. Now, I get JSON in the response instead of the index.html.

How to fix “Uncaught (in promise) SyntaxError: Unexpected token in JSON at position 0” ERROR

"proxy": "http://localhost:8080" 

Above line should be outside the Scripts block below. Because "proxy" is not a part of scripts, but rather a port that talks to the react server see details Like SO:

"scripts": {
"start": "react-scripts start",
"build": "react-scripts build",
"test": "react-scripts test",
"eject": "react-scripts eject"
},
"proxy": "http://localhost:8080"

How to fix Uncaught (in promise) SyntaxError: Unexpected token in JSON at position 0 ERROR

You are getting a JSON back. I just tried to call

async function get() {
  try {
    const res = await fetch(`http://api.openweathermap.org/data/2.5/weather?q=London,uk&appid=079b76b390ad70c628a14a9a141e5992`);
    const json = await res.json();
    console.log('json', json)
  } catch (err) {
    console.error('err', err);
  }

}

It responds with:

{
"coord": {
"lon": -0.13,
"lat": 51.51
},
"weather": [
  {
"id": 520,
"main": "Rain",
"description": "light intensity shower rain",
"icon": "09d"
}
],
"base": "stations",
"main": {
"temp": 285.3,
"pressure": 1004,
"humidity": 93,
"temp_min": 284.15,
"temp_max": 286.48
},
"visibility": 10000,
"wind": {
"speed": 6.2,
"deg": 90
},
"clouds": {
"all": 90
},
"dt": 1571056651,
"sys": {
"type": 1,
"id": 1502,
"message": 0.0096,
"country": "GB",
"sunrise": 1571034113,
"sunset": 1571073060
},
"timezone": 3600,
"id": 2643743,
"name": "London",
"cod": 200
}

You might have missed the http:// part?

Try to use GET and POST, but this error keep using up, Uncaught (in promise) SyntaxError: Unexpected token in JSON at position 0, working on react

You need to add 2 headers Content-Type and Accept equal to application/json.

headers : { 
        'Content-Type': 'application/json',
        'Accept': 'application/json'
}

This will work for you.

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