Fix cors request to flask from javascript fetch

flask_fix_cors.py

from flask import Flask, request, jsonify

def cors(f):
    def fix_cors(*args, **kwargs):
        if request.method == 'OPTIONS':
            response = jsonify('')
            response.headers.add('Access-Control-Allow-Origin',request.headers['Origin'] if 'Origin' in request.headers else '*')
            response.headers.add('Access-Control-Allow-Headers', request.headers['Access-Control-Request-Headers'] if 'Access-Control-Request-Headers' in request.headers else '')
            response.headers.add('Access-Control-Allow-Methods', 'POST, GET, OPTIONS')
            response.headers.add('Access-Control-Max-Age', '86400')
        else:
            return f(*args, **kwargs)
    return fix_cors

@app.route('/', methods=['GET', 'OPTIONS'])
@cors
def profession_api():
    ...
    
    response = jsonify([])
    response.headers.add('Access-Control-Allow-Origin',request.headers['Origin'] if 'Origin' in request.headers else '*')
    
    ...
    return response