Your resource path is not correct, and the exception handler is redundant, because an error won't be raised if the open/read fails (that's not a bug or misfeature - Qt just works differently to Python).
Try something like this, instead:
stream = QFile(':/assets/jquery/js/jquery-1.11.0.min.js')
if stream.open(QFile.ReadOnly):
js = str(stream.readAll(), 'utf-8')
stream.close()
else:
print(stream.errorString())