External library .js is deleted in index.html during build

Ionic Framework ionic-v3
1

Everytime i build - ionic serve my external library is deleted from index.html , is there any configuration for this?

<!DOCTYPE html>
<html lang="en" dir="ltr">
<head>
  <meta charset="UTF-8">
  <title>Ionic App</title>
  <meta name="viewport" content="width=device-width, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0, user-scalable=no">
  <meta name="format-detection" content="telephone=no">
  <meta name="msapplication-tap-highlight" content="no">

  <link rel="icon" type="image/x-icon" href="assets/icon/favicon.ico">
  <link rel="manifest" href="manifest.json">
  <meta name="theme-color" content="#4e8ef7">
 <script type="text/javascript" src="assets/js/lib/excluded/jquery-2.1.3.min.js"></script>
<script type="text/javascript" src="assets/js/lib/aes.js"></script>
<script type="text/javascript" src="assets/js/lib/pbkdf2.js"></script>
<script type="text/javascript" src="assets/js/lib/AesUtil.js"></script>
  <script src="cordova.js"></script>
<link href="build/main.css" rel="stylesheet">

</head>
<body>

  <!-- Ionic's root component and where the app will load -->
  <ion-app></ion-app>

  <!-- The polyfills js is generated during the build process -->
  <script src="build/polyfills.js"></script>

  <!-- The bundle js is generated during the build process -->
  <script src="build/main.js"></script>

</body>
</html>
2

Which index.html are you modifying? There’s one under src, which should be modified, and one under www, which should not be touched.