Flask request.get_json() returns string not json

JSON.stringify() takes a Javascript object and turns it into a JSON string. You're not passing it an object, you're passing it a string, which is then converted into JSON again.

Because the request data contains double-encoded JSON, the request.json attribute gives you back a string rather than a dictionary.

To fix, change:

var myData = '{ "id": "' +clickedID +'" }'

to:

var myData = { id: clickedID }