SyntaxError: Unexpected token \ in JSON at position

Question

I'm trying to parse a String to JSON in NodeJS/Javascript, this is my string (which I cannot change, coming from an external database):

'{\\"value1\\":\\"XYZ\\",\\"value2\\":\\"ZYX\\"}'

I'm calling:

JSON.parse(row.raw_data)

But are getting:

SyntaxError: Unexpected token \ in JSON at position

I actually thought double escape was the correct way of escaping in string/JSON.

Answer 1

Your JSON is invalid. You've said you can't change it, which is unfortunate.

It looks like it's been double-stringified but then the outermost quotes have been left off. If so, you can fix it by adding " at each end and then double-parsing it, like this:

var str = '{\\"value1\\":\\"XYZ\\",\\"value2\\":\\"ZYX\\"}';
str = '"' + str + '"';
var obj = JSON.parse(JSON.parse(str));
console.log(obj);

Ideally, though, you'll want to go through the database and correct the invalid data.

I actually thought double escape was the correct way of escaping in string/JSON.

In JSON, strings are wrapped in double quotes ("), not double escapes. You only escape double quotes within strings (with a single \).

If you've been creating JSON strings manually (in code), don't. :-) Instead, create the structure you want to save, and then stringify it. Building JSON strings manually is error-prone, but a proper JSON stringifier will be reliable.