Here is what worked for me when I deployed to Heroku.
http://flask-cors.readthedocs.org/en/latest/
Install flask-cors by running – pip install -U flask-cors
from flask import Flask
from flask_cors import CORS, cross_origin
app = Flask(__name__)
cors = CORS(app)
app.config['CORS_HEADERS'] = 'Content-Type'
@app.route("/")
@cross_origin()
def helloWorld():
return "Hello, cross-origin-world!"
