Syntaxerror unexpected token in json at position 0

The syntaxerror unexpected token in json at position 0 usually happens while you are working with JSON.

This error is quite difficult and confusing to resolve, especially if you don’t have any idea how to fix it.

Fortunately, this article discusses how to fix uncaught syntaxerror unexpected token u in json at position 0 error.

Aside from that, you’ll also learn important information about this error.

What is JSON?

JSON or JavaScript Object Notation, is a popular data format used for storing and exchanging information between a client and a server.

In addition to that, JSON is one of the most widely used data formats for data transmission. It is a simple format that uses name-value pairs. Strings, arrays, and other types of data that can be serialized are acceptable values.

Here is the example format of JSON:

{
    "name": "fruits",
    "fruits": [
        "apple",
        "banana",
        "citrus",
        "durian",
        "mango",
        "grapes"
  ],
  "favoritefood": {
        "steak": false,
        "pasta": true
  }
}

What is “syntaxerror: unexpected token in json at position 0”?

The syntaxerror: unexpected token in json at position 0 occurs when you are trying to parse something else that is not JSON.

In simple words, you are trying to parse a string to JSON and the string is not parsable.

This error message indicates that there is an issue with the JSON data being parsed.

For example:

const sampleString = '{ "website": "Itsourcecode" }';
const sampleObject = JSON.parse(sampleString);

As you can see in this example, the samplestring variable consists of a string that is a valid JSON. Unfortunately, when a samplestring variable has a JSON string that is not valid, for instance, a string with a syntax error, the JSON.parse() method. Technically error message will arise.

Moreover, the unexpected token u in JSON at position 0 usually raised if you are trying to parse a string as JSON that is not valid JSON.

Why does “unexpected token in json at position 0” error occur?

The syntaxerror: unexpected token u in json at position 0 could be caused by a variety of reasons. Let’s explore some of the common causes such as invalid characters or formatting issues in the JSON data.

👎 When the JSON data structure is not properly formed, such as missing or misplaced brackets, colons, commas, or quotes, the parser may encounter an unexpected token in JSON at position 0″ error.

👎 Unexpected characters can find their way into the JSON data, either due to accidental insertion or encoding issues.

These unexpected characters can cause the parser to stumble upon an unexpected token.

👎 JSON strings should be wrapped in double quotes, and any internal double quotes should be escaped with a backslash (\).

If the JSON data contains invalid string formatting, such as missing or mismatched quotes, the parser may encounter an unexpected token at position 0.

👎 When the JSON data is incomplete, such as missing required fields or closing brackets, the parser may encounter an unexpected token at the beginning, which triggers the error.

How to fix the “syntaxerror unexpected token in json at position 0”?

To fix the uncaught syntaxerror unexpected token u in json at position 0, ensure that the string you are trying to parse as JSON is actually a valid JSON.

You should verify the string for syntax errors and correcting them, or by making it sure that the string you are using is actually JSON and not some other type of data.

Verify the string for syntax errors

const sampleString = '{ "website": "Itsourcecode" }';

try {
  const sampleObject = JSON.parse(sampleString);
  console.log(sampleObject); 
} catch (error) {
  if (error instanceof SyntaxError) {
    console.error('Invalid JSON:', error.message);
  } else {
    throw error;
  }
}

As you can see, we are trying to parse a string to JSON using JSON.parse(). If the string is valid JSON, the JSON.parse() method will return a JavaScript object.

If the string is not valid JSON, a SyntaxError will be thrown.
In the catch block, we check if the error is an instance of SyntaxError. If it is, we log an error message to the console. Otherwise, we re-throw the error.

Output:

{ website: 'Itsourcecode' }

Use a JSON validator to ensure that the JSON data is correctly formatted

You can use a JSON validator to ensure that the JSON data is correctly formatted and free of syntax errors.

For example:

const jsonData = '{"website": "Itsourcecode", "visitors": 5000000, "offer": "Free sourcecodes and tutorial"}';

try {
  JSON.parse(jsonData);
  console.log("JSON data is valid.");
} catch (error) {
  console.log("JSON data is invalid:", error);
}

Output:

JSON data is valid.

Additional solutions for “unexpected token in json at position 0”

✅ Check for Missing or Extra Brackets.

✅ Ensure that special characters within JSON strings are properly escaped using backslashes.

✅ Make sure that all JSON strings are wrapped in double quotes and that internal double quotes are properly escaped.

✅ Check the data source or API from which you’re retrieving the JSON data to ensure it is returning valid JSON.

If you are using local storage when storing the JSON values. Ensure that the values you stored were JSON. If ever you try to store a non -JSON in the local storage.

You’ll have the problem when getting the value from local storage and when you parse it as JSON.

For example:

const sampleObject = {
  key: 'Itsourcecode',
};


const myJSON = JSON.stringify(sampleObject);

localStorage.setItem('myJSON', myJSON);

Here is an example of how you can apply it in an array.

const sampleArray = [10, 20, 30, 40,50];


const myJSON = JSON.stringify(sampleArray);

localStorage.setItem('myJSON', myJSON);

Conclusion

The syntaxerror: unexpected token in json at position 0 occurs when you are trying to parse something else that is not JSON.

We already discussed above what this error is all about and multiple ways to resolve this error.

By executing the solutions above, you can master this Syntaxerror with the help of this guide.

You could also check out other “SyntaxError” articles that may help you in the future if you encounter them.

• Syntaxerror: non-default argument follows default argument
• Syntaxerror: positional argument follows keyword argument
• Syntaxerror: unexpected end of json input

We are hoping that this article helps you fix the error. Thank you for reading itsourcecoders 😊

Caren Bautista

Technical Writer at PIES IT Solution

Responsible for crafting clear, well-structured, and beginner-friendly content across the platform. Handles the writing, proofreading, and editorial review of tutorials, guides, and documentation to ensure every article is accurate, readable, and easy to follow.

Expertise: Technical Writing · Content Creation · Documentation · Editorial Writing · JavaScript · TypeScript · Python · Python Errors · HTTP Errors · MS Excel  · View all posts by Caren Bautista →