TypeScript interface for function with properties

Question

I'm using TypeScript on an Angular.js project and testing with Jasmine.

When I mock a method on an object using spyOn, Jasmine replaces the method with a function that has a calls property so you can do, for instance, thing.method.calls.count().

The problem is that the TypeScript compiler doesn't know about the calls property on the method and gives a compiler error:

property 'calls' does not exist on type '() => IPromise<IReport[]>'

How do I fix this error? Do I need to define a new interface that has a function signature as well as an object property? I've tried monkeying around with different interface configurations, but without luck so far.

Have you pulled in the jasmine.d.ts from the definitely typed repo? — Brocco
– Brocco, Commented Sep 22, 2015 at 21:26

basarat · Accepted Answer · 2015-09-22 23:38:08Z

1

How do I fix this error?

Basically add to the Function interface in a file like globals.d.ts. Demo:

interface Function {
    calls: any;
}

var foo = ()=>null;
foo.calls; // okay

This trick is covered here : https://basarat.gitbooks.io/typescript/content/docs/types/lib.d.ts.html

answered Sep 22, 2015 at 23:38

basarat

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1 Comment

icfantv Over a year ago

I noticed you don't document how to acutally wire in a user-defined global.d.ts file. Can you please elaborate?

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