Add VarDate interface and Date constructor overload for VT_DATE to lib.d.ts

[zspitz]

TypeScript Version: 1.8.0 / nightly (2.0.0-dev.201xxxxx)

Automation host objects pass dates into Javascript as VarDate per the specification (copy found here) (section 2.2.2). These need to be wrapped in a Date constructor before they can be used in Javascript.
Such properties therefore cannot be typed as Date in declarations.

Code

namespace Scripting {
    interface File {
        DateCreated: Date;
    }
    interface FileSystemObject {
        GetFile(FilePath: string): File
    }
}
interface ActiveXObject {
    new (s: 'Scripting.FileSystemObject'): Scripting.FileSystemObject;
}

// Under WSH
var fso = new ActiveXObject('Scripting.FileSystemObject');
var file = fso.GetFile('C:\\test.txt');
var varDate = file.DateCreated;

//the following fails with "'varDate' is null or not an object"
//WScript.Echo(varDate.getYear()); 

//outputs the year
WScript.Echo(new Date(varDate).getYear());

Proposal

Add the following to scripthost.d.ts:

interface VarDate { }

interface DateConstructor {
    new (vd: VarDate): Date;
    getVarDate: () => VarDate;
}

and such date properties could use VarDate instead of Date.

[mhegazy]

ActiveXObject is defined as:

interface ActiveXObject {
    new (s: string): any;
}

so from the compiler perspective fso is of type any.

Contributions for better definitions for the WSH are always welcomed. the definitions should go in https://github.com/Microsoft/TypeScript/blob/master/src/lib/scripthost.d.ts

[zspitz]

Contributions for better definitions for the WSH are always welcomed.

@mhegazy I thought I was the last one using WSH (with or without Typescript)...

[mhegazy]

I thought I was the last one using WSH (with or without Typescript)

:D i think there still a few more out there. the TS compiler uses them internally as well to support running on cscript.

[zspitz]

@mhegazy See here. I've written a tool that uses tlbinf32.dll to generate Typescript definitions from type libraries.

[zspitz]

@mhegazy The tool is now on Github;