[Typescript] Inconsistently handling format of date.

Description

Within the supported typescript frameworks, typescript-fetch and typescript-jquery support format date by transforming it into a javascript Date, while typescript-node and typescript-angular leave them as strings. It would be good to handle format date consistently across Typescript.

Swagger declaration file content or url

{
  "name": "myDate",
  "type": "string",
  "format": "date",
}

Suggest a fix/enhancement

I suggest if the format is a date, we should just leave it as a string following the typescript-node and typescript-angular examples. My concern of turning a YYYY-MM-DD string into a Javascript Date is that depending on your timezone, using toIsoString has the potential to roll your date forward or backwards a day as discussed here.

I encountered a bug in the typescript-fetch library where the code it generates requires an input parameter of a string, but then tries to call a function on it as if it is a Javascript Date object. The fix I suggested would solve this issue as well.

Compare the TypeScript generator behavior in typescript-fetch, typescript-jquery, typescript-node, and typescript-angular for fields declared with string format date. Start by locating how each generator transforms or preserves that format. Done means the supported TypeScript frameworks handle date values consistently and no generated client calls date methods on a string.