ReferenceError: parent is not defined

[and-nord]

Bug Report

Prerequisites

• Can you reproduce the problem in a MWE?

• Are you running the latest version of AngleSharp?
• Did you check the FAQs to see if that helps you?
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Description

I am parsing Kyocera FS-3040MFP+
Index page have frame set

frameset border=0 cols=* frameborder=NO framespacing=0 rows=1,*
frame name=topframe noResize scrolling=no src="../top.htm"
frame name=main src="../start/start.htm"

and javascript that have same vars

<script language="JavaScript"> var opt_msg1_exist = "_mode_on"; if( opt_msg1_exist == "_mode_on") { var opt_msg1_name = '>Português'; } var OEMFlag = 0; if( OEMFlag == 0 || OEMFlag == 2) { document.write('<title>Kyocera Command Center</title>'); document.write(''); } else document.write('<title></title>'); var lang="rus"; var ModelName="FS-3040MFP+"; var IEMsgShown = false; var currentpage=""; var testData = new Array(); testData[0] = 0; var curPageFlag = false; </script>

---

When run start.htm that have into javascript where set var:
Line 45: parent.FaxNum = FaxNum;
Line 48: parent.CipherCheck = 1;
Line 50: parent.CipherCheck = 0;
etc

As result
Script parsing stops with an error "ReferenceError: parent is not defined"

Steps to Reproduce

1. [First Step]
   var srvJsScripting = new JsScriptingService();
   var srvNavigator = new Navigator();
   var config = Configuration.Default.WithDefaultLoader(new LoaderOptions { IsResourceLoadingEnabled = true }).With(srvNavigator)
   .WithLocaleBasedEncoding().WithCulture("ru-ru").With(srvJsScripting);
   var context = BrowsingContext.New(config);
   var queryDocument = context.OpenAsync("http://mfu01.al.loc").Result;

2. [Second Step]
   When page start.htm is was processed throw exception "ReferenceError: parent is not defined" and treatment of script is stopped and run next script where into have "parent.Var = " and this have the same error

3. [and so on...]

Expected behavior:
I want to get variables from the environment of the parent window, read and write data from the child window
Actual behavior:
throw exception "ReferenceError: parent is not defined"
Environment details:
VS 2019, last version of AngleSharp.JS

Possible Solution

Add a property "parent" to the object "Window" to have access to the variables of the parent page
https://developer.mozilla.org/en-US/docs/Web/API/Window/parent

[and-nord]

I found a connection between the current window and the parent. And I was able to get the instance with the variables of the parent window.
var oParent = Window->Document->Context->Parent->Current;
next get instance from document
...\AngleSharp.Js\v.0.14.0\src\AngleSharp.Js\JsScriptingService.cs (line 104)
internal EngineInstance GetOrCreateInstance(IDocument document)
{
var objectContext = document.DefaultView;

        if (!_contexts.TryGetValue(objectContext, out var instance))
        {
            var libs = GetAssemblies(document.Context).ToArray();
            instance = new EngineInstance(objectContext, _external, libs);
            _contexts.Add(objectContext, instance);
        }

        return instance;
    }

It's on my knee, but I would like to get a competent code

[FlorianRappl]

I'll try to look into it! Just quite under water right now...