page.py

import sys
from PyQt5.QtWebEngineWidgets import QWebEnginePage
from PyQt5.QtWidgets import QApplication
from PyQt5.QtCore import QUrl

headers = {
    'user-agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.143 Safari/537.36'}

class Page(QWebEnginePage):
    QA = QApplication(sys.argv)
    
    def __init__(self, url):
        self.app = Page.QA
        QWebEnginePage.__init__(self)
        self.html = ''
        self.loadFinished.connect(self._on_load_finished)
        self.load(QUrl(url))
        self.app.exec_()

    def _on_load_finished(self):
        self.html = self.toHtml(self.Callable)
        print('JavaScript Loaded.')

    def Callable(self, html_str):
        self.html = html_str
        self.app.quit()