JSFiddle - React, Tailwind, and code Playground
HTML
<script src="http://www.google.com/jsapi?fake=.js"></script>
<div id="visualization"></div>
JavaScript
google.load('visualization', '1', {'packages':['corechart']});
google.setOnLoadCallback(drawChart);
function drawChart() {
var data = new google.visualization.DataTable();
data.addColumn({type: 'string', role: 'domain'}, '2009 Quarter');
// tooltip column
data.addColumn({ type: "string", role: "tooltip", p: { html: true }});
data.addColumn('number', '2009 Sales');
data.addColumn('number', '2009 Expenses');
data.addColumn({type: 'string', role: 'domain'}, '2008 Quarter');
data.addColumn('number', '2008 Sales');
data.addColumn('number', '2008 Expenses');
data.addRows([
['Q1 \'09', "<h1>tooltip</h1>", 1000, 400, 'Q1 \'08', 800, 300],
['Q2 \'09', "<h1>tooltip</h1>", 1170, 460, 'Q2 \'08', 750, 400],
['Q3 \'09', "<h1>tooltip</h1>", 660, 1120, 'Q3 \'08', 700, 540],
['Q4 \'09', "<h1>tooltip</h1>", 1030, 540, 'Q4 \'08', 820, 620]
]);
var chart = new google.visualization.LineChart(document.getElementById('visualization'));
chart.draw(data, {width: 400, height: 240, legend:'right', focusTarget: 'category', tooltip: {isHtml: true}});
}