检查打字稿中是否存在函数

Question

我正在将js代码转换为打字稿(角度1到2(...手术痛苦！

下面的行if (_usersDatabase.updateReplication == null) {会导致打字稿错误：

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

.它用于检查函数是否已定义。

请问我怎么能为打字稿写这个？

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

• 无需在打字稿文件中使用'use strict';

• 使用 this 访问他们的方法和变量。

  @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) {
          }
   }
  }