Showing HTML within an iFrame

Hi there,
I want to print a pie chart inside an iFrame.  I have the following code.  When executed,  I am getting an exception saying
"Cannot read property 'getContext' of null"

I am using Charts.js library for creating the pie chart.
Can you please help me with this one.  Thank you.

// in a function I have the following code segment
And I just want to display the pie chart in the iFrame.

function __pieChartExample() {
        var div = document.createElement("div");
        var canvasDiv = document.createElement("canvas"); = "chartArea";
        var ctx = document.getElementById("chartArea").getContext("2d");

        var data = [{
            value : 300,
            color : "#F7464A",
            highlight : "#FF5A5E",
            label : "Red"
        }, {
            value : 50,
            color : "#46BFBD",
            highlight : "#5AD3D1",
            label : "Green"
        }, {
            value : 100,
            color : "#FDB45C",
            highlight : "#FFC870",
            label : "Yellow"

        var pieOptions = {
            segmentShowStroke : false,
            animateScale : true
        new Chart(ctx).Doughnut(data, pieOptions);
        return div;

 function __generateReport() {
        var iFrame = document.createElement("iframe"); = "iFrameID"; = "none";
        var result = iFrame.contentWindow.document.execCommand("save", false, null);
        if (result === false) {

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Hans LangerCommented:
you have the error in:

var ctx = document.getElementById("chartArea").getContext("2d");

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document.getElementById("chartArea") is null so you need to be sure that you have that element in your document and execute your code after the element is loaded with:

window.onload = function(){

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ambuliAuthor Commented:
Thank you
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