Given the following ROUTES: const ROUTES = [ { name: "Login", path: "/login", id: "login" }, { name: "Registration", path: "/registration", id: "registration" }, { name: "Settings", path: "/settings", id: "settings" }, ] as const; How can I create a type (SomeType) for which: every id is used as a key every path is used… Read More Ensure Exhaustiveness and Correctness of Object based on Const Array of Objects

I have a function like this interface Cat { color: string, weight: number, cute: Boolean, // eventhough all cats are cute! } export const doSomething = ( cat: Array<Cat| null>, index: number, key: keyof typeof cat, payload: string | number | Boolean ) => { …. cat[key] = payload …. } This gives me Element… Read More Using dynamic keys on object with typescript

Say I have these TS definitions: export type SearchStackParamList = { SearchScreen: undefined; Restaurant: undefined; }; export type SearchScreenProps = CompositeScreenProps< NativeStackScreenProps<SearchStackParamList, ‘SearchScreen’>, CompositeScreenProps< NativeStackScreenProps<SearchStackParamList>, NativeStackScreenProps<RootStackParamList> > >; export type RestaurantScreenProps = CompositeScreenProps< NativeStackScreenProps<SearchStackParamList, ‘Restaurant’>, CompositeScreenProps< NativeStackScreenProps<SearchStackParamList>, NativeStackScreenProps<RootStackParamList> > >; See how SearchScreenProps and RestaurantScreenProps are kinda redundant? Is there a way I can improve… Read More Avoid repetitive typescript definitions

I did a bad job at asking this question earlier, thought I had the answer, but ended up not having it. I’ve created a typescript playground with the example code. I’m looking to create a function (A) that takes a mapping function (B) as a parameter. The return value of A depends on the return… Read More Return type from function that takes a function as a parameter

I have a type for a "helper" function which receives a context object as first parameter: type helper = ((ctx: Context, …params: any[]) => any); Then I want to create an object of which each value is of the helper type: const lib = { path: (ctx) => ctx.getPath(), array: (ctx, …params) => new MyArray(ctx,… Read More Using TypeScript, is there a way to define an object of which each key is the same type, while preserving the information of which keys are used?

I have function written in typescript where i am passing the object and key as an input parameter and in function return i am expecting the object with key value pair: const article = { id: 1, title: "TypeScript Explained", active: true, getSlug: () => ‘typescript-explained’, }; type Pick<T, U extends keyof T> = {… Read More Access Object property in Typescript

I want to fetch a state’s value, but the problem is that I am receiving state’s name in a parameter. Is there any way to do it directly? (Similar to what is represented in image) >Solution : You have to use the variable in brackets like shown below: function SampleFunc(name){ const ddlValue = this.state[name] }

When extracting a variable from an object, is there a way to already check there if it’s undefined and set a default? I’m basically trying to achieve the below code in one line: let { name } = user name ??= "John" >Solution : let { name = "John" } = user; (destructuring on MDN)

I have this enum I would like to use in my html file: export enum CartAction { ADD = ‘ADD’, REMOVE = ‘REMOVE’, } Currently, it is used in the component ts file as async cartAction(action: CartAction): Promise<void> { if (action === CartAction.ADD) { } if (action === CartAction.REMOVE) { } } And I’d like… Read More How can I pass an enum value as a variable to a function in the Angular html file?

I am trying to construct a function type based on a utility type that is pre-existing, and simply defines a key-to-type mapping: type TypeMap = { a: A; b: B; } The type I am trying to build is a multi-signature function type, using the key as a literal string in the first parameter: type… Read More Mapped function type