Tooltip can be shown on Button hover and it can be achieved by setting title attribute.
The following snippets illustrates how to show tooltip on Button hover.
import { Button } from '@syncfusion/ej2-buttons';
import { enableRipple } from '@syncfusion/ej2-base';
enableRipple(true);
// Initialize the Button component.
let button: Button = new Button({isPrimary: true, content: 'Button'});
// Render initialized button.
button.appendTo('#element');
button.element.setAttribute("title", "Primary Button");<!DOCTYPE html>
<html lang="en">
<head>
<title>EJ2 Button</title>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<meta name="description" content="Typescript UI Controls" />
<meta name="author" content="Syncfusion" />
<link href="//cdn.syncfusion.com/ej2/21.2.3/ej2-base/styles/material.css" rel="stylesheet" />
<link href="//cdn.syncfusion.com/ej2/21.2.3/ej2-buttons/styles/material.css" rel="stylesheet" />
<link href="styles.css" rel="stylesheet" />
<script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
<script src="systemjs.config.js"></script>
</head>
<body>
<div id='loader'>LOADING....</div>
<div id='container'>
<button id='element'></button>
</div>
</body>
</html>#container {
visibility: hidden;
}
#loader {
color: #008cff;
height: 40px;
left: 45%;
position: absolute;
top: 45%;
width: 30%;
}