I think this does the trick: function callMethodWithArgs< M extends keyof T, T extends { [m in M]: (…args: Array<any>) => any }, F extends T[M] >(obj: T, methodName: M, args: Parameters<F>) { return obj[methodName](…args) as ReturnType<F>; } Requires TS 3 though!
That is because TypeScript type system is “structural”, so any two types with the same shape will be assignable one to each other – as opposed to “nominal”, where introducing a new name like Foo would make it non-assignable to a same-shape Bar type, and viceversa. There’s this long standing issue tracking nominal typings additions … Read more
Update 2020: Note that as of now, the global fetch is available on all modern browsers and covers 95% of all web users. If you need support for IE, read the original answer. MDN Doc | TypeScript Definition Where the function is available in the window or global contexts, looks like: fetch(input: RequestInfo, init?: RequestInit): … Read more
What are the proper typescript types for addEventListener mousemove and it’s event argument? Being explicit will set you free: onMouseMove: { (event: MouseEvent): void } = (event: MouseEvent) => { } Or, let TypeScript infer it from assignment 🌹: onMouseMove = (event: MouseEvent) => { }
It sounds like you have a sensible plan. Here are my observations! It is best to make sure you TypeScript depends on your JavaScript and not the other way around where possible. This is because it is very easy to refactor TypeScript using the Visual Studio tools, but it won’t refactor JavaScript that calls your … Read more
You can write an inline type literal for the call signatures the function supports: class TestOverloads2 { private status = “blah”; public doStuff: { (selector: JQuery): void; (selector: string): void; } = (selector: any) => { alert(this.status); } } That’s sort of hideous, so you might want to extract it into an interface instead: interface … Read more
The @ symbol you are referring to is called decorator. Decorators provide a way to add both annotations and a meta-programming syntax for class declarations and members. Basically when you are doing @component you are telling compiler that the class is a angular2 component with the metadata passed as an argument. for eg. @Component({ moduleId: … Read more
This is just a warning that can be safely ignored. We’re working on removing it. You can follow along here: https://github.com/supabase/supabase-js/issues/612
class Apple { appleFoo: any; } class Orange { orangeFoo: any; } var arr : Array<Apple|Orange> = []; var apple = new Apple(); var orange = new Orange(); arr.push(apple); //ok arr.push(orange); //ok arr.push(1); //error arr.push(“abc”); // error var something = arr[0]; if(something instanceof Apple) { something.appleFoo; //ok something.orangeFoo; //error } else if(something instanceof Orange) { … Read more
Change signature of the function, so that generic type T extends type object, introduced in Typescript 2.2. Use this syntax – <T extends object>: function create<T extends object>(prototype: T, pojo: Object): T { … return Object.create(prototype, descriptors) as T; }