You can’t. As a workaround you can use a // @ts-nocheck comment at the top of a file to disable type-checking for that file: https://devblogs.microsoft.com/typescript/announcing-typescript-3-7-beta/ So to disable checking for a block (function, class, etc.), you can move it into its own file, then use the comment/flag above. (This isn’t as flexible as block-based disabling … Read more
You can now use the non-null assertion operator that is here exactly for your use case. It tells TypeScript that even though something looks like it could be null, it can trust you that it’s not: let name1:string = person.name!; // ^ note the exclamation mark here
All fields in JavaScript (and in TypeScript) can have the value null or undefined. You can make the field optional which is different from nullable. interface Employee1 { name: string; salary: number; } var a: Employee1 = { name: ‘Bob’, salary: 40000 }; // OK var b: Employee1 = { name: ‘Bob’ }; // Not … Read more
Let’s say you’re developing a package “A” that have @types/some-module package in devDependencies. For some reason you’re exporting the type from @types/some-module: import { SomeType } from ‘some-module’; export default class APackageClass { constructor(private config: SomeType) { // … } } Right now TypeScript consumers of package “A” are unable to guess what SomeType is, … Read more
Simple answer : class MyClass {} const instance = new MyClass(); console.log(instance.constructor.name); // MyClass console.log(MyClass.name); // MyClass However: beware that the name will likely be different when using minified code.
As stated by drewmoore, the proper solution in this case is to manually trigger change detection for the current component. This is done using the detectChanges() method of the ChangeDetectorRef object (imported from angular2/core), or its markForCheck() method, which also makes any parent components update. Relevant example: import { Component, ChangeDetectorRef, AfterViewInit } from ‘angular2/core’ … Read more
4.19.4 The instanceof operator The instanceof operator requires the left operand to be of type Any, an object type, or a type parameter type, and the right operand to be of type Any or a subtype of the ‘Function’ interface type. The result is always of the Boolean primitive type. So you could use mySprite … Read more
As specified in the documentation, use undefined: export interface INotificationService { error(message: string, title?: string, autoHideAfter? : number); } class X { error(message: string, title?: string, autoHideAfter?: number) { console.log(message, title, autoHideAfter); } } new X().error(“hi there”, undefined, 1000); Playground link.
Your best bet is to throw an Error wrapping the value, which results in a rejected promise with an Error wrapping the value: } catch (error) { throw new Error(400); } You can also just throw the value, but then there’s no stack trace information: } catch (error) { throw 400; } Alternately, return a … Read more
If you know from external means that an expression is not null or undefined, you can use the non-null assertion operator ! to coerce away those types: // Error, some.expr may be null or undefined let x = some.expr.thing; // OK let y = some.expr!.thing;