Plugin won't connect to API

Hello!
I am trying to hookup a plugin to an API.

Basically, I am extracting the local variables from a Figma file and I want to store them in a database. Thus far, I am able to get the variables to my codebase.

I have also built a simple API that adds a row to my database. I know that the API works because I have tested it in Postman and get the expected response.

The function to use this API call in the code looks like this:

async function sendJSONToDB(files) {
  console.log("in download"); // this prints, so I know I have entered the function
  const response = await fetch('http://localhost:3000/api/v1/addColorsRecord', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      'Access-Control-Allow-Origin': '*'
    },
    mode: 'no-cors', // new line
    body: JSON.stringify({
      json_data: files.json_data
    })
  });
  console.log("past fetch") // this does not print, so I never get past the fetch call
  const data = await response.json();

  console.log(data);
 }

Where “files” is an object that looks like this:

let files = {
      json_data: "{}",
      type: "DOWNLOAD"
}

The API function I am calling looks like this:

//POST Method
const addColorsRecord = async (req, res, next) => {
        let conn;
        console.log("in addColorsRecord") // this does not print, so I don't even enter this function
  try {
	conn = await pool.getConnection();
	await conn.query("INSERT INTO COLOR value (?, ?, ?)", [null, req.query.json_data, getCurrentDateTime()]);
    console.log("something has happened")
        const newColorEntry = {
            json_data: req.query.json_data,
            created_on: getCurrentDateTime(),
        };
        res.json(newColorEntry);
    } catch (e) {
        next(e);
    }
};

router.route("/api/v1/addColorsRecord").post(addColorsRecord);

So, any help to figure out why the fetch call is not going through would be much appreciated!
Thanks!