Extension Methods | Typescript

• Extension Methods | Typescript

Primeira forma

export const add = Symbol('add');
function addImpl(this: Date, dateOrMs: number | Date) {
    return new Date(+this + +dateOrMs);
}

export const addDays = Symbol('addDays');
function addDaysImpl(this: Date, days: number) {
    return this[add](days * 24 * 60 * 60 * 1000);
}

declare global {
    export interface Date {
        [add]: typeof addImpl;
        [addDays]: typeof addDaysImpl;
    }
}

Date.prototype[add] = addImpl;
Date.prototype[addDays] = addDaysImpl;
----------------------

//chamando a função
// mostra o import para adicionar

d[add](1).toISOString();

Segunda forma

export default {};

declare global {
  interface String {
    numerize(): number;
    convertToSlug(): string;
  }
}

String.prototype.numerize = function (toFixed: number | null = null): number {
    let value = parseFloat(this);
    value = isNaN(value) || !isFinite(value) ? 0 : value;
    return toFixed ? parseFloat(value.toFixed(toFixed)) : value;
  };
  
  String.prototype.convertToSlug = function (): string {
    let str = this;
    if (!str) {
      return '';
    }
  
    return str.replace(/ +/g, '-').toLowerCase();
  };
  --------------------------------
 import 'arquivo_extension';

  "texto".numerize();

• Esse precisa colocar o import manualmente