Two years after the question was asked, using Visual Studio Command Prompt still did not produce right answer for me. But the usual Help|About window seems working these days:

UPDATE (June 2017):

1. VS 2013 does NOT show this info. (Later note: VS 2017 Enterprise edition does not show this info either).

2. VS uses Microsoft Build Engine (MSBuild) to compile Typescript files. MSBuild can support several major releases of Typescript, but About window shows only the latest one.

Here is how to get to the bottom of it:

A. To check which versions of Typescript are installed with your Visual Studio/MSBuild, inspect contents of C:\Program Files (x86)\Microsoft SDKs\TypeScript folder. For example, I have versions 1.0, 1.8 and 2.2:

B. Check which version of Typescript is requested by your project. In *.csproj file, look for <TypeScriptToolsVersion> tag, or you can add it if it is missing, like this

    <PropertyGroup> 
        ...
        <TypeScriptToolsVersion>1.8</TypeScriptToolsVersion>
        ...
    </PropertyGroup>

C. Finally, you can check, which version of Typescript is actually used by MSBuild. In TOOLS | Options | Projects and Solutions | Build and Run set MSBuild project output verbosity to Detailed:

Then build your project and inspect the output: you should see the reference to one of Typescript folders described in (A).

Since selected correct answer didn't help me I figured I'd share how I resolved the issue.

I had to remove C:\Program Files (x86)\Microsoft SDKs\TypeScript\1.0\ from my PATH.

After that I could run this command and see the version I was expecting:

C:\>tsc --version
message TS6029: Version 1.5.3

When running tsc, it will compile all your source files listed in tsconfig.json. However, when using ts-node/register, it will only error at runtime when attempting to load the require()'d modules.

If you are getting errors on tsc in test:build, try changing the entry point from ./index.ts in build:live to one of the sources that is giving errors. Does it also fail then?

I believe you need to do

npm install -g typescript@latest

or

npm update -g typescript

As answered enter link description here

Open command prompt (cmd.exe/git bash)

Recommended:

npm install -g typescript@latest

or

yarn global add typescript@latest  // if you use yarn package manager

This will install the latest typescript version if not already installed, otherwise it will update the current installation to the latest version.

And then verify which version is installed:

tsc -v

If you have typescript already installed you could also use the following command to update to latest version, but as commentators have reported and I confirm it that the following command does not update to latest (as of now [ Feb 10 '17])!

npm update -g typescript@latest