typescript declare的使用

1. 模块扩展

   // 1.ts
   export class AClass {
     public a:string;
     constructor(a:string) {
       this.a = a;
     }
    }
   

   // 2.ts
   import { AClass } from './1';
   
   declare module './1' {
      interface AClass {
       test: (b: number) => number;
     }
   }
   
   AClass.prototype.test = (b: number): number => {
      return b;
   }
   

2. 全局扩展

    // observable.ts
    export class Observable<T> {
        // ... still no implementation ...
    }

    declare global {
        interface Array<T> {
            toObservable(): Observable<T>;
        }
    }

    Array.prototype.toObservable = function () {
        // ...
    }