檢查打字稿中是否存在函數

Question

我正在將js代碼轉換爲打字稿（角度1到2）......痛苦的操作！

下面if (_usersDatabase.updateReplication == null) {行導致打字稿錯誤：

Typescript Error 
Property 'updateReplication' does not exist on type 'Database<{}>'. 

。它用來檢查函數是否已經定義。

我該如何爲Typescript寫這個？

import { MigrationService } from '../providers/migration-service'; 
import { CouchConstants } from '../couch-constants'; 
import * as PouchDB from 'pouchdb'; 

@Injectable() 
export class UsersDatabase { 

    constructor(
     private storageService: LocalStorageService 
     , private UtilsService: UtilsService 
     , private MigrationService: MigrationService 

    ) { 

    'use strict'; 

    var _usersDatabase = new PouchDB(CouchConstants.COUCHDB_USERS_DB_NAME); 

    if (_usersDatabase.updateReplication == null) { 

     _usersDatabase.updateReplication = function (newDocsIds) { 

Answer 1

• 沒有必要使用this使用'use strict';在打字稿文件

• 訪問他們的方法和變量。

  @Injectable() 
  export class UsersDatabase { 
  private _usersDatabase : any; 
  
  constructor(
      private storageService: LocalStorageService 
      , private UtilsService: UtilsService 
      , private MigrationService: MigrationService 
  
  ) { 
  
  this._usersDatabase = new PouchDB(CouchConstants.COUCHDB_USERS_DB_NAME); 
  
  if (this._usersDatabase.updateReplication == null) { 
  
       this._usersDatabase.updateReplication = function (newDocsIds) { 
  
       } 
  } 
  }