Tuesday, July 14, 2015

Which Version of TypeScript is Installed and Which Version is Visual Studio Using?

My rating of TypeScript on a scale of 1-10... a solid 10

My rating of finding out which version of TypeScript is installed and being used currently... a 2. 

Sometimes the simplest of things are missed and I think this is one of the cases. There is a lot of playing detective and resulting confusion that will come about trying to figure out which versions of TypeScript are actually installed and subsequently, which is targeted for VS.NET to compile against. I'm here to clear up this confusion and shed some light on this for TypeScript users.

The TypeScript compiler (tsc.exe) is installed through the installation of VS.NET 2013 Update 2 (or later versions), VS.NET 2015, or via the TypeScript tools extensions available through the VisualStudio Gallery. VS.NET users of one of the aforementioned versions are in a good place because TypeScript having been created by Microsoft integrates well into VS.NET. Regardless of installation method, the tooling and compilers are available at the following location:

C:\Program Files (x86)\Microsoft SDKs\TypeScript

As can be seen from the screenshot below, I have folders for versions 1.0 and 1.5:

Now before moving further, the way you've probably found to find out which version of TypeScript is installed is to send the -v option to the compiler which will "Print the compiler's version." You can do this from any location using the command prompt. Doing so on a default installation of say VS.NET 2013 with the 1.0 SDK folder present will yield the following:

Notice we have a SDK folder for version 1.0 however the compiler version is This is because what really matters is not the folder, but rather the actual version of the compiler within the folder. In this case the 1.0 folder contains version 1.3 of the TypeScript compiler.

As mentioned, you can run the -v option against the compiler from anywhere. If you run this command against the directory that physically contains the TypeScript compiler (tsc.exe), then the resulting version output will be that of the compiler in the SDK directory targeted.

Running the version command against the 1.0 directory:

Running the version command against the 1.5 directory:

OK great, we can run version commands in different spots and find out about versions of the compiler. However which one are VS.NET and my project using, and where is that compiler version coming from when I run the -v option in a non-TypeScript SDK directory?

Let's address the global version question 1st. You can run the where tsc command from any command line which will tell you the TypeScript compiler location the version is returned from using the version option:

OK so I have SDK tools version 1.0 (compiler version 1.3 as we know) and 1.5 installed. Why is it returning only the tsc.exe information from the 1.0 SDK folder? It turns out that this information is actually a part of the PATH environmental variable in Windows. There is no magic or real installation assessment going on here. It simply reads the directory value embedded within the path variable for TypeScript and finds the tsc.exe version within that specified directory. Here is what was within my Windows PATH variable for TypeScript:

C:\Program Files (x86)\Microsoft SDKs\TypeScript\1.0\

Before we get much further it turns out all these versioning commands, PATH variable values, and the like, they have absolutely no bearing at all on which version of TypeScript VS.NET is using and compiling against. I'll get to that in a minute. 

However every Google search for, "which TypeScript version do I have installed" yields a bunch of results saying, "run tsc -v" which ultimately reads that value in the PATH variable and confuses the heck out of people. They get concerned that VS.NET is not targeting their newer version of TypeScript installed. 

The matter of fact is that TypeScript can have multiple side-by-side installations and it's all about the project's targeted value and none of what's in the PATH variable is important. You would think if the TypeScript team wanted to use the PATH variable they would update it to the newest version upon installing a newer TypeScript version. Not so. It remains stagnant at the old version which then shows the older TypeScript compiler version thus leaving everyone confused.  I found this comment on the following GitHub thread which confirms, folks will have to update the PATH variable manually for the time being:

Before manually changing the PATH variable to point to the newer TypeScript SDK version, lets look at what VS.NET reads to know which compiler to target. Unfortunately it is not available as a nice dropdown in the TypeScript properties for the project (hence adding to my rating of '2' for the version fun with TypeScript). Instead it is in the project's properties configuration within the .csproj or .vbproj file. I particularly like the EditProj Visual Studio Extension which adds a nice 'Edit Project File' to the context menu when right-clicking a project within VS.NET. Doing this will bring up the project's configuration, and I can see the TypeScript version targeted and used by the project inside the tag:

Now VS.NET will append this value to the C:\Program Files (x86)\Microsoft SDKs\TypeScript\ path to get the compiler used for the project. In this case we know from above the 1.3 version of the TypeScript compiler is in that directory. 

Let's do a test and write some TypeScript using the spread operator that's not fully supported until ES6 or version 1.5 of TypeScript which can compile to ES5 JavaScript. Technically version 1.3 of TypeScript can still compile the following to JS but it will complain in the IDE which is what we'd expect:

Notice how we get the red squiggly under the spread operator usage (three dots ...) and a notice that this is a TypeScript 1.5 feature.

Now we can prove the tsc -v output and resulting PATH variable value are not what's being used by VS.NET (it's the Tools Version I showed above). If we change the PATH variable TypeScript directory value from:

C:\Program Files (x86)\Microsoft SDKs\TypeScript\1.0\


C:\Program Files (x86)\Microsoft SDKs\TypeScript\1.5\

...in the System variables (the TypeScript directory is embedded within the Path variable, so copy out to Notepad to locate and modify):

...and open a new command window we can see now the tsc -v command reads the updated PATH variable and outputs the resulting 1.5.0 version. 

So cool right? VS.NET should now reflect version 1.5 of TypeScript being used and our warning should go away. Nope. Save your TypeScript file, rebuild, reopen VS.NET, do whatever you feel, and you will still see the warning above. That's because what matters to VS.NET is what version is in it's own project configuration and not what the PATH variable returns via the version command.

What we need to do is manually update the project's configuration to point to the 1.5 SDK tools version (remember this should be the value of the folder that VS.NET appends to the SDK directory and not the actual compiler version). Using the 'Edit Project' tool I mentioned previously, I can change the 1.0 tools version to 1.5:

If I go back to my TypeScript file, immediately I notice the spread command is understood and accepted as we are pointing to version 1.5 of the TypeScript compiler:

So that's TypeScript versioning as of today. If you want to target a newer (or older) version of TypeScript, or just want to see which version your project is currently using, you'll need to take a look in the project's configuration for the  value.

As an aside, VS.NET will warn you if you have a newer version of the TypeScript tools installed, but your project is targeting an older version. It will ask if you would like to upgrade your project:

I can say I've had mixed results saying  'Yes' to this dialog including while writing this post. It did not update the version to 1.5 in my project's properties. I still had to manually modify the version.

To this end, I've made a recommendation on Microsoft Connect that the TypeScript tools version (and corresponding compiler version), be selectable from within the IDE on the 'TypeScript Build' tab within the project's properties. You can read and vote for this if you would like here: Allow switching TypeScript configured version from Project Properties IDE


  1. I just upgraded from Typescript 1.5 to 1.6, got the warning dialog about the typescript version being used not being the latest installed. I clicked Yes to use the latest and my csproj file was edited correctly.

  2. A programming language should be judged in large part by the ecosystem and tooling it provides. I agree with the spirit of your assessment of TypeScript's utility and language design (relatively high, even if it's nowhere near a 10), but its tooling is seriously spotty in quality. Your ranking of "2" in one of the most basic of capabilities (determining which version you are using for your code) belies the "10" you give the language overall. The designers of TypeScript have done a terrible job of supporting their community and providing consistent tooling. A 10 should be reserved for something you can't find a flaw in. Your article is proof that Typescript is very, very far from a 10 overall. Do you really think a programming language that requires a how-to article on figuring out what version will be used to compile your project deserves a "10"?

  3. I followed this, but when actually downgrading VS2015 TS Compiler (from 1.7.2 to 1.6.2) because of incompatibility issues with "this" operator. I was only half successful though. Code is compiled by 1.6 tsc, but Visual Studio's code editor still underlines 1.7 incompatible code in red. Any thoughts?

  4. THank you. This cleared a lot of things for me.

  5. Great article. It explained a lot. I'm still having compilation errors, but has definitely helped me in not going down a rabbit hole on my typescript compilation errors investigation. I see that I'm in the right version for my project, so the error is somewhere else.

  6. Thank you for a clear explanation! Great post.

  7. I'm using VS 2013, and the project file was pointing to the typescript 1.4 folder. I wanted to upgrade to 1.8. The folder was already there, so I edited the project file, reloaded, etc., but VS still used an older version of tsc.exe. I then downloaded the installation file for Typescript 1.8.2 for Visual Studio 2013, via online nuget search (Tools | Extensions and Updates). After installing, it was clear that VS was using a later version of tsc.exe (I only checked if the namespace keyword was recognized). Oddly, though, when I checked nuget (Tools | Extensions and Updates) for installed libraries, it did NOT show that TS 1.8.2 was installed. It's lying!

  8. Excellent POST - thank you for sharing your knowledge. Solved my problems!