How to declare interfaces using TypeScript
An interface defines how something behaves, without defining the implementation. In TypeScript, an interface names a complex type by describing the fields it has. This is known as structural subtyping.
How to do it…
Declaring an interface is a little like declaring a structure or class; you define the fields in the interface, each with its own type, like this:
interface Record { call: string; lat: number; lng: number; } Function printLocation(r: Record) { console.log(r.call + ': ' + r.lat + ', ' + r.lng); } var myObj = {call: 'kf6gpe-7', lat: 21.9749, lng: 159.3686}; printLocation(myObj);
How it works…
The interface
keyword in TypeScript defines an interface; as I already noted, an interface consists of the fields it declares with their types. In this listing, I defined a plain JavaScript object, myObj
and then called the function printLocation
, that I previously defined, which takes a Record
. When calling printLocation
with myObj
, the TypeScript...