下面的代码在所有浏览器中都可以正常打开，但是当我尝试在 WPF Web 浏览器控件中运行代码时，它给出了 Javascript 错误“canvas.getContext("2d") 未定义”。
<html>
<head>
<title>Bar Chart</title>
<script src="Chart.js" type="text/javascript"></script>
<script type="text/javascript">
var canvas = null;
var context = null;
window.onload = function () {
invokeService();
canvas = document.getElementById("canvas");
var context = canvas.getContext("2d");
alert(context);
var myLine = new Chart(document.getElementById("canvas").getContext("2d")).Bar(barChartData);
};
var barChartData;
function invokeService() {
alert("q");
barChartData = {
labels: ["January", "February", "March", "April", "May", "June", "July"],
datasets: [
{
fillColor: "rgba(220,220,220,0.5)",
strokeColor: "rgba(220,220,220,1)",
data: [65, 59, 90, 81, 56, 55, 40]
},
{
fillColor: "rgba(151,187,205,0.5)", …