我是 html5 和 javascript 的新手。
第一次尝试创建 html5、javascript、css3 饼图**（不使用 jquery）**。饼图可以在 chrome 和 firefox 中完美创建。然后过了一会儿，我不小心在Internet Explorer（IE）中打开了index.html，饼图不见了。后来我意识到即使是 Komodo 的浏览器也不显示饼图。
试过了
1）谷歌，看到了一个叫做 excanvas.js 的东西。
2）在 index.html 中包含这一行
<!-- can't post script with arrow bracket in stackoverflow, uncomment & replace < with |-->
<!-- |script src="./js/excanvas.js"||/script|-->
3）在 pie_chart_simple.js 的 initialize_para() 函数中包含这一行，
if(typeof canvas.getContext==='undefined')return;
结果：
仍然无法在 Internet Explorer 中查看饼图。（仅显示表格值）
不确定性： 1）excanvas.js 的使用？（由于没有使用jquery，放置代码的位置） 2）ie解码的颜色格式？
介意帮忙吗？谢谢你。
有2个文件：
1）index.html：
2)pie_chart_simple.js
（jsfiddle 链接：http: //jsfiddle.net/torresho/wmJb6/6/）
1) index.html
<!DOCTYPE html>
<html>
<head>
<title>Pie Chart</title>
<meta name="viewport" content="width=device-width, initial-scale=1" />
<!-- can't post script with arrow bracket in stackoverflow, uncomment & replace < with |-->
<!-- |script src="./js/excanvas.js"||/script|-->
<!-- |script type="text/javascript" src="./js/pie_chart_simple.js"||/script| -->
</head>
<body>
<div id="container">
<canvas id="chart" width="380" height="460"></canvas>
<table id="chartData">
<tr>
<th>Club</th><th>Points</th>
</tr>
<tr style="color: #0DA068">
<td>MU</td><td>71</td>
</tr>
<tr style="color: #194E9C">
<td>MC</td><td>59</td>
</tr>
<tr style="color: #ED9C13">
<td>Tot</td><td>54</td>
</tr>
<tr style="color: #ED5713">
<td>Chel</td><td>52</td>
</tr>
<tr style="color: #057249">
<td>Ars</td><td>52</td>
</tr>
</table>
</div>
</body>
</html>
2) pie_chart_simple.js：
// jquery method // Run the code when the DOM is ready
//$( pie_chart_simple );
window.onload=function(){
pie_chart_simple();
}
function pie_chart_simple() {
// Pie Chart Configuration Settings
var chartSizePercent = 55; // The chart radius relative to the canvas width/height (in percent)
var chartStartAngle = -0.5 * Math.PI; // Start the chart at 12 o'clock instead of 3 o'clock
var sliceGradientColour = "#ddd"; // Colour to use for one end of the chart gradient (#ddd = RGB(211,211,211) = light grey)
// Variables for the chart
var canvas; // The canvas element in the page
var canvasWidth; // Width of the canvas, in pixels
var canvasHeight; // Height of the canvas, in pixels
var centreX; // X-coordinate of centre of the canvas/chart
var centreY; // Y-coordinate of centre of the canvas/chart
var chartRadius; // Radius of the pie chart, in pixels
var table; // The table element in the page
var numRows; // The number of rows in the table
var label_array = []; // An array to store the first column values (labels)
var value_array = []; // An array to store the 2nd column values (values)
var chartColors = []; // Chart colors (pulled from the HTML table)
var totalValue = 0; // Total of all the values in the chart
var startAngle = []; // Start angle of each slice
var endAngle = []; // End angle of each slice
var startX =0;
var startY =0;
var change_color=0;
initialize_para();
/********************************** Initialization - starto************************************************/
function initialize_para() {
// Define the canvas element
canvas = document.getElementById('chart');
console.log(canvas);
console.log('canvas='+canvas);
console.log(canvas.getContext);
console.log(typeof canvas.getContext);
console.log(typeof canvas.getContext==='undefined');
// Check if the browser does not support canvas (e.g. ie)
// code goes here...
// Exit if the browser isn't canvas-capable
if ( typeof canvas.getContext === 'undefined' ) return;
// Acquire the parameters to determine the chart size
canvasWidth = canvas.width;
canvasHeight = canvas.height;
centreX = canvasWidth/2;
centreY = canvasHeight/2;
chartRadius = (Math.min(canvasWidth,canvasHeight)/2)*(chartSizePercent/100);
//alert('canvasWidth='+canvasWidth+', canvasHeight='+canvasHeight+' ,chartRadius='+chartRadius); //popup
console.log('canvasWidth='+canvasWidth+', canvasHeight='+canvasHeight+' ,chartRadius='+chartRadius); //log
// Get the pie chart data - labels, values and color (from the html table)
// Alternatively, can be simplified using each() in jquery
table = document.getElementById('chartData');
numRows = table.rows.length;
for (var i = 1; i<numRows; i++) {
var trs = table.getElementsByTagName('tr')[i];
label_array[i-1] = trs.cells[0].innerText; // label
value_array[i-1] = trs.cells[1].innerText; // value
chartColors[i-1] = trs.style.color; // color
totalValue += parseFloat(value_array[i-1]); // total value
console.log(label_array[i-1]+' '+value_array[i-1]+' '+chartColors[i-1]+' '+totalValue);
// MU 71 rgb(13, 160, 104) 71
// MC 59 rgb(25, 78, 156) 130
// Tot 54 rgb(237, 156, 19) 184
// Chel 52 rgb(237, 87, 19) 236
// Ars 52 rgb(5, 114, 73) 288
}
// Compute and store the start and end angles of each slice of the data
var currentPos = 0; //The current position of the slice in the pie(from 0 to 1)
// (3/2)pi radians / -ve pi/2 radians
// ^
// |<
// | ) (starting point is here ccw direction, when drawing in canvas)
//1pi radians-----|----> 0pi radians / 2pi radians
// |
// |
// pi/2 radians
for (var i = 0; i<numRows-1; i++) {
//console.log(i+' '+2*currentPos+'PI');
startAngle[i] = 2*Math.PI*currentPos;
endAngle[i] = 2*Math.PI*(currentPos+(value_array[i]/totalValue));
currentPos += value_array[i]/totalValue;
console.log(i+' '+'Slice'+' '+(i+1)+' StartAngle: '+startAngle[i]+' EndAngle: '+endAngle[i]);
// 0 Slice 1 StartAngle: 0 EndAngle: 1.5489797111449675 pie_chart_simple.js:80
// 1 Slice 2 StartAngle: 1.5489797111449675 EndAngle: 2.8361600344907854 pie_chart_simple.js:80
// 2 Slice 3 StartAngle: 2.8361600344907854 EndAngle: 4.014257279586958 pie_chart_simple.js:80
// 3 Slice 4 StartAngle: 4.014257279586958 EndAngle: 5.148721293383272 pie_chart_simple.js:80
// 4 Slice 5 StartAngle: 5.148721293383272 EndAngle: 6.283185307179586
}
// After working out all the data needed for the chart, draw the chart
drawChart();
//$('#chart').click ( handleChartClick ); // jQuery way
// element.onclick = functionRef;
//canvas.onclick = handleChartClick;
}
/********************************** Initialization - endo************************************************/
/********************************** Draw chart - starto************************************************/
function drawChart() {
// Get the drawing context (canvas tag is use to draw graphics on the fly)
// getContext() method returns an object that provides methods and properties for drawing on the canvas
var context = canvas.getContext('2d');
// Clear the canvas, ready for the new frame
// (x-coordinate of upper-left corner, y-coordinate of upper-left corner,
// width of the rectangle to clear (in pixles), height of the rectangle to clear (in pixels))
context.clearRect(0,0,canvasWidth,canvasHeight);
// Draw an individual slice in the chart iteratively to form a complete circular pie chart
for (slice_number=0; slice_number<numRows-1; slice_number++) {
drawSlice(context,slice_number);
}
} //function drawChart() ends
function drawSlice(context,slice_number) {
// Compute the adjusted start and end angles for the slice (start at 12 o'clock instead of 3 o'clock)
var startAngle_offset = startAngle[slice_number] + chartStartAngle;
var endAngle_offset = endAngle[slice_number] + chartStartAngle;
// Draw the pie from the centre
startX = centreX;
startY = centreY;
// Set the gradient fill for the slice
var sliceGradient = context.createLinearGradient(0,0,canvasWidth*0.75,canvasHeight*0.75);
sliceGradient.addColorStop(0, sliceGradientColour);
sliceGradient.addColorStop(1, chartColors[slice_number]);
//liceGradient.addColorStop(1,'#fff');
//???????????
//sliceGradient.addColorStop(0,"black");
//sliceGradient.addColorStop(1,"white");
//console.log('startAngle_offset='+startAngle_offset+', endAngle_offset='+endAngle_offset); //log
//console.log('startX='+startX+', startY='+startY); //log
//console.log('sliceGradient='+sliceGradient+', sliceGradient.addColorStop(0, sliceGradientColour)='+sliceGradient.addColorStop(0, sliceGradientColour)); //log
//console.log('sliceGradient.addColorStop(1)='+sliceGradient.addColorStop(1,'#fff')+', sliceGradientColour='+sliceGradientColour); //log
//console.log('chartColors[slice_number]='+chartColors[slice_number]+', slice_number='+slice_number); //log
//console.log(' -----');
// Draw the slice
context.beginPath();
context.moveTo(startX,startY);
context.arc(startX,startY,chartRadius,startAngle_offset,endAngle_offset,false); //last field optional. Specifies whether the drawing should be counterclockwise or clockwise. False=clockwise, true=counter-clockwise
context.lineTo(startX,startY);
context.closePath();
if (change_color == 1) {
context.fillStyle = "rgba(0,0,0,0)";
}
else{
context.fillStyle = sliceGradient;}
context.fill();
context.shadowColor = "rgba(0,0,0,0)";
// Draw the slice border
context.stroke();
// add label
context.fillText(label_array[slice_number],startX+slice_number*10+100,startY+slice_number*10+100);
context.fillText(value_array[slice_number],startX+slice_number*10+100,startY+slice_number*10+100+20);
}
/********************************** Draw chart - endo ************************************************/
} // function pie_chart_simple() ends