[Python] Why does Flask redirect to "GET /? HTTP/1.1"

I'm writing a simple Flask application in which I want to send some data from the front-end to the Flask app, have it perform some operations, and return new data to the front-end for display. I have made similar applications before, and by returning the POST response object, instead of render_template(), I'm able to simply return the data and do what I want with it on the front-end. However, this time I'm having problems.

I make a POST request from the Jquery in the front-end. Everything seems to work fine, I can see the data being returned in the browser console, except the page reloads before I can display the new data. It reloads to http://xxx.x.x.x:5000/?.

I can see the get request for /? in the Flask console. I'd like to know why it is doing this, and how I can get it to stop.

(I've found this difficult to research because most search engines will silently ignore any question marks in a query.)

Flask app:

import json
from flask import Flask, Response, render_template, request
from src.simple_lookup import analogy_lookup

app = Flask(__name__)
app.config['DEBUG'] = True

@app.route('/')
def hello_world():
return render_template('index.html', results=['a', 'b'])

@app.route('/get_words_simple', methods=['POST'])
def get_words_simple():
print('request.form:', request.form.keys)
data = analogy_lookup(request.form['keyword'], request.form['base'], request.form['goal'])
resp = Response(json.dumps(data), status=200, mimetype='application/json')
print('data:', data)
print('resp:', resp)
return resp

if __name__ == "__main__":
app.run()


Jquery:

$.post('get_words_simple?', data, function(json, status) {
console.log('response:', json);
if (json.hasOwnProperty('error')) {
$('.results').append('<p>' + json.error);
return;
}

var words = json.words;
$.each(words, function(i, text) {
var p = $("<p>");
p.append(text);
$('.results').append(p);
});
});


Flask console:

127.0.0.1 - - [27/Dec/2018 11:12:21] "GET / HTTP/1.1" 200 -
127.0.0.1 - - [27/Dec/2018 11:12:21] "GET /static/js/main.js HTTP/1.1" 200 -
request.form: <bound method MultiDict.keys of ImmutableMultiDict([('keyword', ''), ('base', ''), ('goal', '')])>
127.0.0.1 - - [27/Dec/2018 11:12:23] "GET /? HTTP/1.1" 200 -
127.0.0.1 - - [27/Dec/2018 11:12:23] "GET /static/js/main.js HTTP/1.1" 200 -
data: ['obtuvo', 'takata', 'stadshypotek', 'kriwet', 'shafiee', 'martorell', 'collum', '29,400', 'muteesa', 'patzek']
resp: <Response 111 bytes [200 OK]>
127.0.0.1 - - [27/Dec/2018 11:12:23] "POST /get_words_simple? HTTP/1.1" 200 -

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