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MSDN covers the topic of JavaScript and WinRT type conversions provided by Chakra (JavaScript Representation of Windows Runtime Types and Considerations when Using the Windows Runtime API), but for the questions I get about it I’ll try to lay out some specifics of that discussion more plainly. I’ve made a TL;DR JavaScript types and WinRT types summary table.

WinRT	Conversion	JavaScript
Struct	↔️	JavaScript object with matching property names
Class or interface instance	➡	JavaScript object with matching property names
Windows.Foundation.Collections.IPropertySet	➡	JavaScript object with arbitrary property names
Any	⃠	DOM object

Chakra, the JavaScript engine powering the Edge browser and JavaScript Windows Store apps, does the work to project WinRT into JavaScript. It is responsible for, among other things, converting back and forth between JavaScript types and WinRT types. Some basics are intuitive, like a JavaScript string is converted back and forth with WinRT’s string representation. For other basic types check out the MSDN links at the top of the page. For structs, interface instances, class instances, and objects things are more complicated.

A struct, class instance, or interface instance in WinRT is projected into JavaScript as a JavaScript object with corresponding property names and values. This JavaScript object representation of a WinRT type can be passed into other WinRT APIs that take the same underlying type as a parameter. This JavaScript object is special in that Chakra keeps a reference to the underlying WinRT object and so it can be reused with other WinRT APIs.

However, if you start with plain JavaScript objects and want to interact with WinRT APIs that take non-basic WinRT types, your options are less plentiful. You can use a plain JavaScript object as a WinRT struct, so long as the property names on the JavaScript object match the WinRT struct’s. Chakra will implicitly create an instance of the WinRT struct for you when you call a WinRT method that takes that WinRT struct as a parameter and fill in the WinRT struct’s values with the values from the corresponding properties on your JavaScript object.

// C# WinRT component
        public struct ExampleStruct
        {
            public string String;
            public int Int;
        }

        public sealed class ExampleStructContainer
        {
            ExampleStruct value;
            public void Set(ExampleStruct value)
            {
                this.value = value;
            }

            public ExampleStruct Get()
            {
                return this.value;
            }
        }

// JS code
        var structContainer = new ExampleWinRTComponent.ExampleNamespace.ExampleStructContainer();
        structContainer.set({ string: "abc", int: 123 });
        console.log("structContainer.get(): " + JSON.stringify(structContainer.get()));
        // structContainer.get(): {"string":"abc","int":123}

You cannot have a plain JavaScript object and use it as a WinRT class instance or WinRT interface instance. Chakra does not provide such a conversion even with ES6 classes.

You cannot take a JavaScript object with arbitrary property names that are unknown at compile time and don’t correspond to a specific WinRT struct and pass that into a WinRT method. If you need to do this, you have to write additional JavaScript code to explicitly convert your arbitrary JavaScript object into an array of property name and value pairs or something else that could be represented in WinRT.

However, the other direction you can do. An instance of a Windows.Foundation.Collections.IPropertySet implementation in WinRT is projected into JavaScript as a JavaScript object with property names and values corresponding to the key and value pairs in the IPropertySet. In this way you can project a WinRT object as a JavaScript object with arbitrary property names and types. But again, the reverse is not possible. Chakra will not convert an arbitrary JavaScript object into an IPropertySet.

// C# WinRT component
        public sealed class PropertySetContainer
        {
            private Windows.Foundation.Collections.IPropertySet otherValue = null;

            public Windows.Foundation.Collections.IPropertySet other
            {
                get
                {
                    return otherValue;
                }
                set
                {
                    otherValue = value;
                }
            }
        }

        public sealed class PropertySet : Windows.Foundation.Collections.IPropertySet
        {
            private IDictionary map = new Dictionary();

            public PropertySet()
            {
                map.Add("abc", "def");
                map.Add("ghi", "jkl");
                map.Add("mno", "pqr");
            }
            // ... rest of PropertySet implementation is simple wrapper around the map member.
            

// JS code
    var propertySet = new ExampleWinRTComponent.ExampleNamespace.PropertySet();
    console.log("propertySet: " + JSON.stringify(propertySet));
    // propertySet: {"abc":"def","ghi":"jkl","mno":"pqr"}

    var propertySetContainer = new ExampleWinRTComponent.ExampleNamespace.PropertySetContainer();
    propertySetContainer.other = propertySet;
    console.log("propertySetContainer.other: " + JSON.stringify(propertySetContainer.other));
    // propertySetContainer.other: {"abc":"def","ghi":"jkl","mno":"pqr"}

    try {
        propertySetContainer.other = { "123": "456", "789": "012" };
    }
    catch (e) {
        console.error("Error setting propertySetContainer.other: " + e);
        // Error setting propertySetContainer.other: TypeError: Type mismatch
}

There’s also no way to implicitly convert a DOM object into a WinRT type. If you want to write third party WinRT code that interacts with the DOM, you must do so indirectly and explicitly in JavaScript code that is interacting with your third party WinRT. You’ll have to extract the information you want from your DOM objects to pass into WinRT methods and similarly have to pass messages out from WinRT that say what actions the JavaScript should perform on the DOM.

Some time back while I was working on getting the Javascript Windows Store app platform running on Windows Phone (now available on the last Windows Phone release!) I had an interesting bug that in retrospect is amusing.

I had just finished a work item to get accessibility working for JS WinPhone apps when I got a new bug: With some set of JS apps, accessibility appeared to be totally broken. At that time in development the only mechanism we had to test accessibility was a test tool that runs on the PC, connects to the phone, and dumps out the accessibility tree of whatever app is running on the phone. In this bug, the tool would spin for a while and then timeout with an error and no accessibility information.

My first thought was this was an issue in my new accessibility code. However, debugging with breakpoints on my code I could see none of my code was run nor the code that should call it. The code that called that code was a more generic messaging system that hit my breakpoints constantly.

Rather than trying to work backward from the failure point, I decided to try and narrow down the repro and work forwards from there. One thing all the apps with the bug had in common was their usage of WinJS, but not all WinJS apps demonstrated the issue. Using a binary search approach on one such app I removed unrelated app code until all that was left was the app's usage of the WinJS AppBar and the bug still occurred. I replaced the WinJS AppBar usage with direct usage of the underlying AppBar WinRT APIs and continued.

Only some calls to the AppBar WinRT object produced the issue:

        var appBar = Windows.UI.WebUI.Core.WebUICommandBar.getForCurrentView(); 
        // appBar.opacity = 1;
        // appBar.closeDisplayMode = Windows.UI.WebUI.Core.WebUICommandBarClosedDisplayMode.default;
        appBar.backgroundColor = Windows.UI.Colors.white; // Bug! 

Just setting the background color appeared to cause the issue and I didn't even have to display the AppBar. Through additional trial and error I was blown away to discover that some colors I would set caused the issue and other colors did not. Black wouldn't cause the issue but transparent black would. So would aqua but not white.

I eventually realized that predefined WinRT color values like Windows.UI.Colors.aqua would cause the issue while JS literal based colors didn't cause the issue (Windows.UI.Color is a WinRT struct which projects in JS as a JS literal object with the struct members as JS object properties so its easy to write something like {r: 0, g: 0, b: 0, a: 0} to make a color) and I had been mixing both in my tests without realizing there would be a difference. I debugged into the backgroundColor property setter that consumed the WinRT color struct to see what was different between Windows.UI.Colors.black and {a: 1, r: 0, g: 0, b: 0} and found the two structs to be byte wise exactly the same.

On a hunch I tried my test app with only a reference to the color and otherwise no interaction with the AppBar and not doing anything with the actual reference to the color: Windows.UI.Colors.black;. This too caused the issue. I knew that the implementation for these WinRT const values live in a DLL and guessed that something in the code to create these predefined colors was causing the issue. I debugged in and no luck. Now I also have experienced crusty code that would do exciting things in its DllMain, the function that's called when a DLL is loaded into the process so I tried modifying my C++ code to simply LoadLibrary the DLL containing the WinRT color definition, windows.ui.xaml.dll and found the bug still occurred! A short lived moment of relief as the world seemed to make sense again.

Debugging into DllMain nothing interesting happened. There were interesting calls in there to be sure, but all of them behind conditions that were false. I was again stumped. On another hunch I tried renaming the DLL and only LoadLibrary'ing it and the bug went away. I took a different DLL renamed it windows.ui.xaml.dll and tried LoadLibrary'ing that and the bug came back. Just the name of the DLL was causing the issue.

I searched for the DLL name in our source code index and found hits in the accessibility tool. Grinning I opened the source to find that the accessibility tool's phone side service was trying to determine if a process belonged to a XAML app or not because XAML apps had a different accessibility contract. It did this by checking to see if windows.ui.xaml.dll was loaded in the target process.

At this point I got to fix my main issue and open several new bugs for the variety of problems I had just run into. This is a how to on writing software that is difficult to debug.

PowerShell nicely includes ConvertTo-CSV and ConvertFrom-CSV which allow you to serialize and deserialize your PowerShell objects to and from CSV. Unfortunately the CSV produced by ConvertTo-CSV is not easily opened by Excel which expects by default different sets of delimiters and such. Looking online you'll find folks who recommend using automation via COM to create a new Excel instance and copy over the data in that fashion. This turns out to be very slow and impractical if you have large sets of data. However you can use automation to open CSV files with not the default set of delimiters. So the following isn't the best but it gets Excel to open a CSV file produced via ConvertTo-CSV and is faster than the other options:

Param([Parameter(Mandatory=$true)][string]$Path);

$excel = New-Object -ComObject Excel.Application

$xlWindows=2
$xlDelimited=1 # 1 = delimited, 2 = fixed width
$xlTextQualifierDoubleQuote=1 # 1= doublt quote, -4142 = no delim, 2 = single quote
$consequitiveDelim = $False;
$tabDelim = $False;
$semicolonDelim = $False;
$commaDelim = $True;
$StartRow=1
$Semicolon=$True

$excel.visible=$true
$excel.workbooks.OpenText($Path,$xlWindows,$StartRow,$xlDelimited,$xlTextQualifierDoubleQuote,$consequitiveDelim,$tabDelim,$semicolonDelim, $commaDelim);

See Workbooks.OpenText documentation for more information.

With Facebook changing its privacy policy and settings so frequently and just generally the huge amount of social sites out there, for many of us it is far too late to ensure our name doesn't show up with unfortunate results in web searches. Information is too easily copyable and archive-able to make removing these results a viable option, so clearly the solution is to create more data.

Create fake profiles on Facebook using your name but with a different photo, different date of birth, and different hometown. Create enough doppelgangers to add noise to the search results for your name. And have them share embarrassing stories on their blogs. The goal is to ensure that the din of your alternates drowns out anything embarrassing showing up for you.

Although it will look suspicious if you're the only name on Google with such chaff. So clearly you must also do this for your friends and family. Really you'll be doing them a favor.

I've been working on the Glitch Helperator. It is a collection of tools and things I've put together for Glitch. It has a few features that I haven't seen elsewhere including:

Favorite Streets

A notebook in which you can save information about interesting streets and later use it to find your way back to them.

Birthday

Find out how old your Glitch is and the date of your next birthday in Glitch time or Earth time.

API Update History

A history of changes to the streets, skills and achievements of Glitch noting when new ones are added and when existing ones are changed.

It also has an interactive skill tree, find nearest feature tool, and achievement display. If you play Glitch, check it out.

Most existing DRM attempts to only allow the user to access the DRM'ed content with particular applications or with particular credentials so that if the file is shared it won't be useful to others. A better solution is to encode any of the user's horrible secrets into unique versions of the DRM'ed content so that the user won't want to share it. Entangle the users and the content provider's secrets together in one document and accordingly their interests. I call this Blackmail DRM. For an implementation it is important to point out that the user's horrible secret doesn't need to be verified as accurate, but merely verified as believable.

Apparently I need to get these blog posts written faster because only recently I read about Social DRM which is a light weight version of my idea but with a misleading name. Instead of horrible secrets, they say they'll use personal information like the user's name in the DRM'ed content. More of my thoughts stolen and before I even had a chance to think of it first!