javascript - Cannot initialize a pie chart with Chart.js -

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i copying example chart.js , stuck error making is.

here code (taken examples):

<canvas id="mychart" width="400" height="400"></canvas> <script src="https://code.jquery.com/jquery-2.1.4.min.js"></script> <script src=" https://cdnjs.cloudflare.com/ajax/libs/chart.js/1.0.2/chart.min.js" charset="utf-8"></script> <script type="text/javascript">     // context of canvas element want select     var ctx = document.getelementbyid("mychart").getcontext("2d");     var mynewchart = new chart(ctx[0]).pie(data);     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"     }] </script>

this code gives me error:

uncaught typeerror: cannot read property 'canvas' of undefined

now if change mynewchart var to:

var mynewchart = new chart(ctx).pie(data);

i no error , no chart.

what missing? feel it's obvious...

thanks

two issues code.

first, assigning properties data after it's passed chart(), pie chart appear empty since not passing data.

second, .getcontext('2d') not return array singular rendering context (or null). ctx[0] undefined.

modify code follows , should work.

var ctx = document.getelementbyid("mychart").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 mynewchart = new chart(ctx).pie(data);

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