title: ionic Object(...) is not a function at DocumentViewer.viewDocument :
body: <p>I'm trying to load a pdf from the assets folder in ionic or to download one. I've watched some tutorials but all of them are giving me the same error.</p>
  
  <p>Ionic:</p>
  
  <ul>
  <li>ionic (Ionic CLI)  : 4.1.2 (C:\Users\hanna\node_modules\ionic)</li>
  <li>Ionic Framework    : ionic-angular 3.9.3</li>
  <li>@ionic/app-scripts : 3.2.1</li>
  </ul>
  
  <p>Cordova:</p>
  
  <ul>
  <li>cordova (Cordova CLI) : 8.1.2 (cordova-lib@8.1.1)</li>
  <li>Cordova Platforms     : android 6.4.0, browser 5.0.4</li>
  <li>Cordova Plugins       : cordova-plugin-ionic-keyboard 2.1.3, cordova-plugin-ionic-webview 3.1.2, (and 7 other plugins)</li>
  </ul>
  
  <p>System:</p>
  
  <ul>
  <li>NodeJS : v9.4.0 (C:\Program Files\nodejs\node.exe)</li>
  <li>npm    : 5.6.0</li>
  <li>OS     : Windows 10</li>
  </ul>
  
  <p>The code :</p>
  
  <pre><code>import { Component } from '@angular/core';
  import { DocumentViewer, DocumentViewerOptions } from '@ionic- 
  native/document-viewer/ngx';
  import { FileOpener } from '@ionic-native/file-opener/ngx';
  import { FileTransfer } from '@ionic-native/file-transfer/ngx';
  import { File } from '@ionic-native/File/ngx';
  import { NavController, Platform } from 'ionic-angular';
  
  @Component({
    selector: 'page-home',
  templateUrl: 'home.html'
  })
  export class HomePage {
   constructor(
  public navCtrl: NavController,
  private file: File,
  private ft: FileTransfer,
  private document: DocumentViewer,
  public platform: Platform
  ) {}
  openLocalPdf() {
  // let filePath = this.file.applicationDirectory + 'www/assets';
  
      // if (this.platform.is('android') || this.platform.is('browser')) {
  //   let fakeName = Date.now();
  //   this.file.copyFile(filePath, 'Typescript_Jumpstart_Book_Udemy.pdf', this.file.dataDirectory, `${fakeName}.pdf`).then(result =&gt; {
  //     this.fileOpener.open(result.nativeURL, 'application/pdf')
  //       .then(() =&gt; console.log('File is opened'))
  //       .catch(e =&gt; console.log('Error opening file', e));
  //   })
  // } else {
  //   // Use Document viewer for iOS for a better UI
  //   const options: DocumentViewerOptions = {
  //     title: 'My PDF'
  //   }
  //   this.document.viewDocument(`${filePath}/5-tools.pdf`, 'application/pdf', options);
  // }
  console.log('Documents Pressed.....');
  
      const options: DocumentViewerOptions = {
    title: "My PDF"
  }
  this.document.viewDocument('assets/Typescript_Jumpstart_Book_Udemy.pdf', 'application/pdf', options)
  console.log('Documents Pressed..... afterrr');
  
    }
    downloadAndOpenPdf() {
  let path = null;
  if (this.platform.is('ios')) {
    path = this.file.documentsDirectory;
  } else {
    path = this.file.dataDirectory;
  }
  
      const transfer = this.ft.create();
  transfer.download('https://devdactic.com/html/5-simple-hacks-LBT.pdf', path + 'MyFile.pdf').then(entry =&gt; {
    let url = entry.toURL();
  
        this.document.viewDocument(url, 'application/pdf', {});
    // this.fileOpener.open(url, 'application/pdf')
    // .then(() =&gt; console.log('File is opened'))
    // .catch(e =&gt; console.log('Error opening file', e));
   });
    }
  }
  </code></pre>
  
  <p>the Error is :</p>
  
  <pre><code>ERROR TypeError: Object(...) is not a function
  at DocumentViewer.viewDocument (index.js:29)
  at HomePage.webpackJsonp.193.HomePage.openLocalPdf (home.ts:43)
  at Object.eval [as handleEvent] (HomePage.html:10)
  at handleEvent (core.js:13589)
  at callWithDebugContext (core.js:15098)
  at Object.debugHandleEvent [as handleEvent] (core.js:14685)
  at dispatchEvent (core.js:10004)
  at core.js:10629
  at HTMLButtonElement.&lt;anonymous&gt; (platform-browser.js:2628)
  at t.invokeTask (polyfills.js:3)
  </code></pre>