Multiple type signatures for members, Union Types in TypeScript

Question

If I have a property that might be a string or a boolean how do I define it:

interface Foo{     bar:string;     bar:boolean; } 

I don't want to resort to:

interface Foo{     bar:any; } 

I don't think its possible without any. You can answer any of these:

Have I overlooked a spec and its possible right now? Is something like this planned? Has a feature request been logged?

I would imagine something like this:

interface Foo{     bar:string;     bar:boolean;     bar:any;  }  var x:Foo = <any>{}; x.bar="asdf"; x.bar.toUpperCase(); // intellisence only for string  

Answer 1

As of 2015, union-types work:

interface Foo {     bar:string|boolean; } 

Answer 2

This is usually referred to as "union types". The TypeScript type system from 1.4 does allow for this.

See: Advanced Types