Category "typescript-generics"

TypeScript: Is it possible to safely access nested properties of an object given an array of keys? Can this be done in a type safe and composable way?

I'd like to write a function which gets a value from an object given an array of property keys. It would look something like this: function getValue<O, K ext

How to narrow down the union type of a class generic?

This class holds either a single Item or an array of items Item[], determined by a setting at runtime (this.config.isMultiple). How can I narrow down the class'

TypeScript failes to infer return type of constrained generic function in some cases, why is this happening?

I have this code, which works just fine in a simple case, meaning the "permissionList" const is type inferred, VSCode can suggest me the properties, such as "pe

Typescript: Type 'Promise<void>' is not assignable to type 'void | Destructor'

The editor is showing Type 'Promise' is not assignable to type 'void | Destructor'. for the checkUserLoggedIn() call in useEffect. I can get rid of it by doin

ndarray type annotation typescript

I created a function that creates an array from a given shape with typescript. But how do I specify the return type of that function as it will vary depending o

Create child class object from parent class static method typescript

I have two classes User and Model User class extends Base class Model. class User extends Model {} Model class has a static method createFrom static createFrom

TypeScript create type from generic argument

Say I create an instance of my class like: var x = new SomeClass<SomeModel>() Where the definitions are: interface SomeModel{ someString: string so

Typescript generic object in array only match the specified Records

Demo: https://tsplay.dev/Nnavaw So I have an array with the following definition: Array<{ id?: string; text?: string; date?: Date; }>

Typescript: Evaluate type of generic function

Is there any trick to "evaluate" the type of a generic fuction? Consider the following: type Arr = <A>() => A[] type Ev<G, A> = ??? Question: I

Build a complex type from Union type

I'm trying to build a type with two layers from a flat union type Here's my code: type TextVariants = | { size: 'tiny' // available variants for t

How to use union type as a generic parameter in a record which in a function

I'm confused about the generic union type in Record. This is my code (TypeScript version: 4.6.3): const fn = <T extends number | string = string>() =&g

How do I create a generic factory method that access static members of the class type it's creating

I'm using Typescript to write REST API endpoints as Functions over Firebase, and the methods all follow a similar pattern: check for a request.body, pull the ap

function declaration for a generic function return wrapper

How to declare the function wraps that takes any function and returns a version of it that differs only in returning an object that wraps the original return ty

TypeScript Generics column.id should be within row[key]

I'm writing a TypeScript Interface for Tables: interface Column { id: string; label: string; } interface Data { [key: string]: string; } interfac