Here’s another way to think about it. Consider four sets: Blue things, red things, big things, and small things. If you intersect the set of all blue things and all small things, you end up with the union of the properties — everything in the set has both the blue property and the small property. … Read more
Here is the simplest solution without Service or Observer: Put the global variables in a file and export them. // // ===== File globals.ts // ‘use strict’; export const sep=”https://stackoverflow.com/”; export const version: string=”22.2.2″; To use globals in another file, use an import statement: import * as myGlobals from ‘globals’; Example: // // ===== File … Read more
It’s very simple. Just install the definitions that you need via npm. For example if you need lodash you can do: npm install –save @types/lodash Once it’s installed you can use it right away in your project. Typescript will resolve the typings for the installed @types package from the node_modules/@types folder by default. There’s no … Read more
Upgrading to “ts-node”: “10.8.1” solved the issue for me.
That’s called Type Assertion or casting. These are the same: let square = <Square>{}; let square = {} as Square; Example: interface Props { x: number; y: number; name: string; } let a = {}; a.x = 3; // error: Property ‘x’ does not exist on type `{}` So you can do: let a = … Read more
A few tips in order restart the terminal restart the machine reinstall nodejs + then run npm install typescript -g If it still doesn’t work run npm config get prefix to see where npm install -g is putting files (append bin to the output) and make sure that they are in the path (the node … Read more
I believe this is because objects are contravariant in their key types. For more information see this answer. Likewise, multiple candidates for the same type variable in contra-variant positions causes an intersection type to be inferred. const paths = [‘a’, ‘b’] as const type Path = typeof paths[number] type PathMap = { [path in Path]: … Read more
UPDATE for TS 4.1: TypeScript 4.1 introduced a –noUncheckedIndexedAccess compiler flag that implements the suggestion in microsoft/TypeScript#13778 to account for undefined in this way. Note that the feature will not be enabled as part of the –strict set of compiler options and is being called “pedantic index signatures” because it will end up complaining about … Read more
I don’t know what things were like in the alpha, but I’m using beta 12 right now and this works fine. If you have an array of objects, create a select like this: <select [(ngModel)]=”simpleValue”> // value is a string or number <option *ngFor=”let obj of objArray” [value]=”obj.value”>{{obj.name}}</option> </select> If you want to match on … Read more
TypeScript 3.4 added const assertions which allow for writing this as: const fruits = [“Apple”, “Orange”, “Pear”] as const; type Fruits = typeof fruits[number]; // “Apple” | “Orange” | “Pear” With as const TypeScript infers the type of fruits above as readonly[“Apple”, “Orange”, “Pear”]. Previously, it would infer it as string[], preventing typeof fruits[number] from … Read more