Create Extension Method in typescript - String.IsNullOrEmpty()

How to Create Extension Method using Typescript in Angular Application - String.IsNullOrEmpty()

Step 1 : Create typings.d.ts (declaration file) in the application and declare the method in interface like below.

HTML
interface StringConstructor {
    isNullOrEmpty(value: string): boolean;
}

Step 2 : Create extension.ts file in the application and implement the method like below.

HTML
String.isNullOrEmpty = function (value: string): boolean {
  return value === undefined || value.trim() === '' || value === null;
};

Step 3 : Usage of the Method in the component or class file.

HTML
import './extensions';

export class TestComponent implements OnInit {

  public ngOnInit(): void {

  let abc;

  console.log(String.isNullOrEmpty(abc));

  }

}

Step 4 : Output like below.


Comments

Popular posts from this blog

Create Custom Form Control for ng-select in Angular

Send API POST Request in MS SQL Server

Difference of High-Level Design (HLD) and Low-Level Design (LLD)

Tightly Coupled and Loosely Coupled in .NET Core with example

Configure the API gateway in Microservices Architecture with example in .NET Core

Create a function to convert from string to Decimal using JavaScript

Export to Excel in Angular 6 | 7 | 8 | 9 | 10

Angular CLI Commands - Cheat Sheet

Recommended Visual Studio Code Extensions for Angular Development

Content Negotiation in Web API with example