Unexpected token u in JSON at position 0 code example

Example 1: Uncaught (in promise) SyntaxError: Unexpected token O in JSON at position 0

var stringified = JSON.stringify(data);
var parsedObj = JSON.parse(stringified);
 
console.log(parsedObj);

Example 2: SyntaxError: Unexpected token u in JSON at

That error is normally seen when the value given to JSON.parse is actually undefined. 
So, I would check the code that is trying to parse this - most likely you are not parsing the actual string shown here.

Example 3: fetch SyntaxError: Unexpected token < in JSON at position 0

JSON.parse(theStringThatIsNotJson);

Example 4: unexpected token s in json at position 0

var s = '"something"';
var result = JSON.parse(s);