I'm pretty new to JavaScript and HTML5. I'm trying to print a normal line chart onto canvas using Chart.js. I followed the step by step guide on their website, but am unable to make the graph show.
This is the current code:
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>CHARTS</title>
<script src="../../../Downloads/Chart.js-master/Chart.js"></script>
</head>
<body>
<canvas id="myCanvas" width="800" height="500" style="border:dashed #FF0000">Aw Snap!</canvas>
<script>
context = document.getElementById('myCanvas').getContext('2d');
var data = {
labels : ["January","February","March","April","May","June","July"],
datasets : [
{
fillColor : "rgba(220,220,220,0.5)",
strokeColor : "rgba(220,220,220,1)",
pointColor : "rgba(220,220,220,1)",
pointStrokeColor : "#fff",
data : [65,59,90,81,56,55,40]
},
{
fillColor : "rgba(151,187,205,0.5)",
strokeColor : "rgba(151,187,205,1)",
pointColor : "rgba(151,187,205,1)",
pointStrokeColor : "#fff",
data : [28,48,40,19,96,27,100]
}
]
}
Line.defaults = {
//Boolean - If we show the scale above the chart data
scaleOverlay : false,
//Boolean - If we want to override with a hard coded scale
scaleOverride : false,
//** Required if scaleOverride is true **
//Number - The number of steps in a hard coded scale
scaleSteps : null,
//Number - The value jump in the hard coded scale
scaleStepWidth : null,
//Number - The scale starting value
scaleStartValue : null,
//String - Colour of the scale line
scaleLineColor : "rgba(0,0,0,.1)",
//Number - Pixel width of the scale line
scaleLineWidth : 1,
//Boolean - Whether to show labels on the scale
scaleShowLabels : true,
//Interpolated JS string - can access value
scaleLabel : "<%=value%>",
//String - Scale label font declaration for the scale label
scaleFontFamily : "'Arial'",
//Number - Scale label font size in pixels
scaleFontSize : 12,
//String - Scale label font weight style
scaleFontStyle : "normal",
//String - Scale label font colour
scaleFontColor : "#666",
///Boolean - Whether grid lines are shown across the chart
scaleShowGridLines : true,
//String - Colour of the grid lines
scaleGridLineColor : "rgba(0,0,0,.05)",
//Number - Width of the grid lines
scaleGridLineWidth : 1,
//Boolean - Whether the line is curved between points
bezierCurve : true,
//Boolean - Whether to show a dot for each point
pointDot : true,
//Number - Radius of each point dot in pixels
pointDotRadius : 3,
//Number - Pixel width of point dot stroke
pointDotStrokeWidth : 1,
//Boolean - Whether to show a stroke for datasets
datasetStroke : true,
//Number - Pixel width of dataset stroke
datasetStrokeWidth : 2,
//Boolean - Whether to fill the dataset with a colour
datasetFill : true,
//Boolean - Whether to animate the chart
animation : true,
//Number - Number of animation steps
animationSteps : 60,
//String - Animation easing effect
animationEasing : "easeOutQuart",
//Function - Fires when the animation is plete
onAnimationComplete : null
}
new Chart(context).Line(data,options);
</script>
</body>
What am I doing wrong that is causing my chart to not show?
I'm pretty new to JavaScript and HTML5. I'm trying to print a normal line chart onto canvas using Chart.js. I followed the step by step guide on their website, but am unable to make the graph show.
This is the current code:
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>CHARTS</title>
<script src="../../../Downloads/Chart.js-master/Chart.js"></script>
</head>
<body>
<canvas id="myCanvas" width="800" height="500" style="border:dashed #FF0000">Aw Snap!</canvas>
<script>
context = document.getElementById('myCanvas').getContext('2d');
var data = {
labels : ["January","February","March","April","May","June","July"],
datasets : [
{
fillColor : "rgba(220,220,220,0.5)",
strokeColor : "rgba(220,220,220,1)",
pointColor : "rgba(220,220,220,1)",
pointStrokeColor : "#fff",
data : [65,59,90,81,56,55,40]
},
{
fillColor : "rgba(151,187,205,0.5)",
strokeColor : "rgba(151,187,205,1)",
pointColor : "rgba(151,187,205,1)",
pointStrokeColor : "#fff",
data : [28,48,40,19,96,27,100]
}
]
}
Line.defaults = {
//Boolean - If we show the scale above the chart data
scaleOverlay : false,
//Boolean - If we want to override with a hard coded scale
scaleOverride : false,
//** Required if scaleOverride is true **
//Number - The number of steps in a hard coded scale
scaleSteps : null,
//Number - The value jump in the hard coded scale
scaleStepWidth : null,
//Number - The scale starting value
scaleStartValue : null,
//String - Colour of the scale line
scaleLineColor : "rgba(0,0,0,.1)",
//Number - Pixel width of the scale line
scaleLineWidth : 1,
//Boolean - Whether to show labels on the scale
scaleShowLabels : true,
//Interpolated JS string - can access value
scaleLabel : "<%=value%>",
//String - Scale label font declaration for the scale label
scaleFontFamily : "'Arial'",
//Number - Scale label font size in pixels
scaleFontSize : 12,
//String - Scale label font weight style
scaleFontStyle : "normal",
//String - Scale label font colour
scaleFontColor : "#666",
///Boolean - Whether grid lines are shown across the chart
scaleShowGridLines : true,
//String - Colour of the grid lines
scaleGridLineColor : "rgba(0,0,0,.05)",
//Number - Width of the grid lines
scaleGridLineWidth : 1,
//Boolean - Whether the line is curved between points
bezierCurve : true,
//Boolean - Whether to show a dot for each point
pointDot : true,
//Number - Radius of each point dot in pixels
pointDotRadius : 3,
//Number - Pixel width of point dot stroke
pointDotStrokeWidth : 1,
//Boolean - Whether to show a stroke for datasets
datasetStroke : true,
//Number - Pixel width of dataset stroke
datasetStrokeWidth : 2,
//Boolean - Whether to fill the dataset with a colour
datasetFill : true,
//Boolean - Whether to animate the chart
animation : true,
//Number - Number of animation steps
animationSteps : 60,
//String - Animation easing effect
animationEasing : "easeOutQuart",
//Function - Fires when the animation is plete
onAnimationComplete : null
}
new Chart(context).Line(data,options);
</script>
</body>
What am I doing wrong that is causing my chart to not show?
Share Improve this question edited Jun 26, 2017 at 20:46 Tot Zam 8,79611 gold badges55 silver badges79 bronze badges asked Dec 4, 2013 at 16:25 Abdul JabbarAbdul Jabbar 2,5735 gold badges27 silver badges45 bronze badges3 Answers
Reset to default 2Data variable is not yet initialized when you are calling "new Chart". Move the "new Chart" to end of JS block.
A tip - to check for errors use JS console.
Edit: The were two additional JavaScript errors - options variable was not intialized and Line was undefined variable. Please check my reply below for demo link.
You didn't declared the options variable either pass an empty array for options.
new Chart(context).Line(data,{});
Or declare the variable
var options = { ... }
new Chart(context).Line(data, options);
I think I have a solution to 'options' problem. If you remove options from:
new Chart(context).Line(data,options);
so it looks like that:
new Chart(context).Line(data);
does it work?
It is because
Line.defaults = { ... }
is just a list of options you may change - you are not supposed to put the whole thing to your html file.
In other words instead of for example:
Line.defaults = { scaleOverlay : true, scaleOverride : true }
try:
var options = { scaleOverlay : true, scaleOverride : true }
The tutorial on the homepage of chartjs is confusing in this regard a little bit because it tells you to use an array of settings that are default in the main file. But you are supposed to just take the "insides" and use them, not the whole thing and it does not say to actually create options variable for it. It took me an hour to figure out but only because I have made a mistake of not checking up JS Console immediatelly, as @Lauris hinted out in his answer :)
Also make sure that this:
<script src="../../../Downloads/Chart.js-master/Chart.js"></script>
points to a correct file. It looks like you just did that to hide the real path from StackOverflow munity. In that case nevermind.
I hope this helps!