Replaces tagName of your app's main component with ion-app.
npm i -S ionic-selectorYou don't even have to specify a selector of your main component.
It's the app by default.
import ionicSelector from 'ionic-selector';
ionicSelector('app'); // or blank or any selector you wantBefore:
<body>
<app class="main"></app>
</body>After:
<body>
<ion-app class="main"></ion-app>
</body>