Is an array of types possible in Typescript?

Question

I use the following pattern in Javascript:

var things = {
  "blue": BlueThing,
  "heavy": HeavyThing,
  "imaginary": ImaginaryThing
};

var my_thing = things[thing_type]();

I'm migrating the codebase to Typescript, and I can't find a way to achieve the same thing. I've defined a Thing interface, and the relevant classes. Is there a way to achieve this sort of dynamic instantiation without resorting to a big case statement?

@TomMillard The point is I can't create a things dictionary in TypeScript since types have no type. — fredley
– fredley, Commented Apr 18, 2017 at 16:18
Typescript is a superset of JavaScript, and all valid Javascript is also valid Typescript. Therefore, it's not really clear what issue you are having, or why this code doesn't work as is. — Claies
– Claies, Commented Apr 18, 2017 at 16:18

fredley · Accepted Answer · 2017-04-18 16:35:25Z

0

OK, I sorted this out.

Using the constructor interface pattern, I now have this:

interface ThingConstructor {
  new (options: {[key: string]: string}) : Thing
}

interface Thing{
  /* * */
}

function thingFactory(type: ThingConstructor) : Function{
  return function(options) : Thing {
    return new type(options)
  }
}

--------

things: {[key: string]: Function}

--------

things["blue"] = thingFactory(BlueThing)

var my_thing = things[thing_type]({"stripes": "vertical"})

edited Apr 18, 2017 at 16:35

answered Apr 18, 2017 at 16:28

fredley

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1 Comment

MinusFour Over a year ago

Maybe specify the function type too? (options) => Thing

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