I need to implement the following (simplified) Typescript Interface of an d.ts file:
interface SomeLibrary {
someProperty: SomePropertyClass;
someMethod();
(someParam: string): SomeClass; // don't know hot to implement this
}
How do I implement this interface in an own class? Especially the unnamed method is problematic. How are those methods called?
The interface you have shown can't be satisfied by a class in TypeScript.
Interfaces like this are usually created to describe a library that uses a different pattern.
One example of how you can satisfy the interface is shown below:
var example: SomeLibrary = <any> function(someParam: string) {
console.log('function called');
return new SomeClass();
}
example.someProperty = new SomePropertyClass();
example.someMethod = function () { console.log('method called'); };
var x = example('x');
var y = example.someProperty;
var z = example.someMethod();
<any> in this example mean?
someProperty and someMethod members). For this reason, you need to wiggle the type to tell the compiler I know that this type will be okay, even though it doesn't look like it is to you. If you forgot to add the next two lines, you'd cause a runtime problem though!any, so it can then be narrowed by the preceding SomeLibrary type annotation.