var xhr = new XMLHttpRequest();
...
function setPost() {
    xhr.open("POST", '/home/ioprst/work/app/tmp/get_data.py', true)
    ...
}

 from flask import Flask
from flask import render_template
from flask import send_file
 
app = Flask(__name__)
 
@app.route("/")
def index():
    return send_file('templates/index.html')
 
@app.route("/<fname>", methods=['GET'])
def page(fname):
    return send_file('templates/' + fname)
 
if __name__ == "__main__":
    app.run(host='0.0.0.0')

 xhr.open("POST", '/get-data', true)

 from get_data import get_data
 
@app.route('/get-data', methods=['POST'])
def get():
    data = request.get_data().decode('utf-8')
    return get_data(data)