title: Uncaught (in promise): ReferenceError: Strophe is not defined
body: <p>Why I am getting <strong>Strophe is not defined</strong> this type of error, when i install Strophe properly as per solution in this link:  <strong><a href="https://forum.ionicframework.com/t/integrate-quickblox-in-ionic-2/81726" rel="nofollow noreferrer">https://forum.ionicframework.com/t/integrate-quickblox-in-ionic-2/81726</a></strong></p>
  
  <p>First i have install strophe.js using,
    <strong>npm install strophe.js</strong></p>
  
  <p>then install Strophe using <strong>npm install strophe</strong></p>
  
  <p>then add in index.html file: 
     script src="strophe.js"</p>
  
  <p>and .ts file code is:</p>
  
  <pre><code>import * as $ from "jquery";
  import * as quickblox from "quickblox";
  import * as Strophe from 'Strophe';
  
  CREDENTIALS:any = {
   appId: 73870,
   authKey: 'ffzhPELMPfcZ8ZK',
   authSecret: '7a-VJ6dsBNT77t7'
  };
  
  user:any = {
   id: 24786158,
   login: 'test',
   pass: 'qwerty1234'
  };
  
  quickblox.init(this.CREDENTIALS.appId, this.CREDENTIALS.authKey, this.CREDENTIALS.authSecret);
  quickblox.createSession(
    {login: this.user.login, password: this.user.pass},
    (err, result) =&gt; { //THIS LINE HAS BEEN CHANGED &lt;-
      if (result){
        quickblox.chat.connect(
          {userId: this.user.id, password: this.user.pass},
          (err, roster) =&gt; { //THIS ONE TOO &lt;-
            if (err){
              console.log(err);
            }
          });
      }       
      console.log(err);
      console.log(result);
  });
  
  if anybody have solution to solve this issue, please help me here.
  </code></pre>