Visual Studio 2015 giving "TS1110 Type expected." for numeric literal type union alias

Question

My general setup is this:

Visual Studio 2015
.NET Framework 4.5.2

I would like to start refactoring some client-side code from javascript to typescript. To start this process, I:

• Added a .ts file to the web project
• Let Visual Studio configure itself to compile typescript
• Installed the jquery.Typescript.DefinitelyTyped Nu-Get package v3.1.2
• Copied my existing typescript code into the new file

All's good except one of my type alias declarations. I made a simple demonstration of the error at the top of my file to show the issue.

Visual Studio has no problem with a string literal type alias , but doesn't like the numeric literal type alias .

Visual Studio is reporting the version of TypeScript installed as 1.8.36.0 .

Answer 1

In typescript 1.8, numeric literal type aliases aren't implemented yet, only string literal aliases .

Visual Studio 2015 will let you update your version of TypeScript tools to a newer one (though not the newest version, since the team has since moved on from supporting 2015).

• Got to Tools > Extensions and Updates...
• Click Online ,
• Type typescript 3.1.1 into the search bar. That is the most recent version that Visual Studio 2015 supports as of this writing.
• Clicking download will redirect you to your browser to download the installer.
• Install away, then restart visual studio.

It should now be using the version of typescript that you installed. You can check what version it's using under Help > About Microsoft Visual Studio .

If it didn't install correctly, edit the relevant .csproj file and change the contents of the element TypeScriptToolsVersion from 1.8 to 3.1 .