JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>

<html>
	<head>
		<meta charset="utf-8">
		<link rel="stylesheet" type="text/css" href="CSS/styles.css">
		<link rel="stylesheet" type="text/css" href="CSS/weater-icons.css">
		<link rel="stylesheet" type="text/css" href="CSS/weather-icons.min.css">
		<link rel="stylesheet" type="text/css" href="CSS/weather-icons.wind.css">
		<link rel="stylesheet" type="text/css" href="CSS/weather-icons.wind.min.css">
	</head>		
		<body>
			<div class="page">
				<header>
					<title>Rückblick</title>
					<nav>
						<div class="navigation">
							<p><a href="index.php">Homepage</a></p>
							<p><a href="vorhersage.php">Wettervorhersage</a></p>
							<p><a href="rückblick.php">Rückblick</a></p>
							<p><a href="AQKollektiv.php">Luftqualität</a></p>
						</div>
					</nav>
				</header>
				<figure>
					<div id="chartContainer1" style="width: 80%; height: 100%; margin: auto;"></div>	
					<figcaption></figcaption>
				</figure>
				<br/>
					<form name ="chooseGraph" method="POST" action="#">
					  <input type="radio" name="radio" id="graphTag" value="tag"> Tagesgraph<br>
					  <input type="radio" name="radio" id="graphWeek" value="woche"> Wochengraph<br>
					  <input type="submit" name="submit" value="Zeige Graph" />
					  
					    <?php 

						/*if (isset($_POST['submit'])) {
						if(isset($_POST['radio']))
						{
						echo "You have selected :".$_POST['radio'];  //  Displaying Selected Value
						}    
						*/ 
						?>
						
					</form>	 
				<footer>	
				</footer>
			</div>
		</body>
</html>

JavaScript

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/canvasjs/1.7.0/jquery.canvasjs.min.js"></script>
<script type="text/javascript">

var tempTagGraph;
var luftfTagGraph;

if(document.getElementById('graphTag').checked) {
  //Male radio button is checked
}else if(document.getElementById('graphWeek').checked) {
  //Female radio button is checked
}
	
  });
});


$(document).ready(function () {
	
	var resulttemp;
	var resulthumidity;
	
	$.ajaxSetup({
		async: false
	});
	
	$.getJSON("tempTag.php", function(result){
		resulttemp = result;
	});
	$.getJSON("luftfTag.php", function(result){
		resulthumidity = result;
	});

	function showGraph(resulttemp, resulthumidity) {

		var chart = new CanvasJS.Chart("chartContainer1", {
			animationEnabled: true,
			theme: "light2",
			title:{
				text: "Temperatur und Luftfeuchtigkeit"
			},
			
			legend: {
				cursor: "pointer",
				itemclick: function (e) {
					//console.log("legend click: " + e.dataPointIndex);
					//console.log(e);
					if (typeof (e.dataSeries.visible) === "undefined" || e.dataSeries.visible) {
						e.dataSeries.visible = false;
					} else {
						e.dataSeries.visible = true;
					}

					e.chart.render();
				}
			},
			
			axisY: {
					includeZero: true
			},
			
			axisX:{ 
					labelFormatter: function (e) {
					return CanvasJS.formatDate( e.value, "DD-MM-YY");
			},
			labelAngle: -50},
			
			data: [{
				type: "line",
				name: "Temperatur",
				yValueFormatString: "##.## °C",
				showInLegend: true,
				dataPoints: resulttemp
			},{
				type: "line",
				name: "Luftfeuchtigkeit",
				yvalueFormatString: "#0.00 %",
				showInLegend: true,
				dataPoints: resulthumidity
			}]	
			});

		chart.render();
	};
	showGraph(resulttemp, resulthumidity);
});	
</script>