JavaScript Graphics
Chart.js
Chart.js comes with the following built-in chart types:
- Scatter
- Line
- Bar
- Radar
- Pie and Doughnut
- Polar Area
- Bubble
How to Use Chart.js?
Chart.js is easy to use.
First, add a link to the providing CDN (Content Delivery Network):
<script
src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.9.4/Chart.js">
</script>
Then, add a <canvas> to where you want to draw the chart:
<canvas id="myChart" style="width:100%;max-width:700px"></canvas>
The canvas element must have a unique id.
That's all!
Typical Scatter Chart Syntax:
var myChart = new Chart("myChart", {
type: "scatter",
data: {},
options: {}
});
Typical Line Chart Syntax:
var myChart = new Chart("myChart", {
type: "line",
data: {},
options: {}
});
Typical Bar Chart Syntax:
var myChart = new Chart("myChart", {
type: "bar",
data: {},
options: {}
});
Scatter Plots
House Prices vs. Size
Source Code
var xyValues = [
{x:50, y:7},
{x:60, y:8},
{x:70, y:8},
{x:80, y:9},
{x:90, y:9},
{x:100, y:9},
{x:110, y:10},
{x:120, y:11},
{x:130, y:14},
{x:140, y:14},
{x:150, y:15}
];
new Chart("myChart", {
type: "scatter",
data: {
datasets: [{
pointRadius: 4,
pointBackgroundColor: "rgba(0,0,255,1)",
data: xyValues
}]
},
options:{...}
});
Line Graphs
House Prices vs. Size
Source Code
var xValues = [50,60,70,80,90,100,110,120,130,140,150];
var yValues = [7,8,8,9,9,9,10,11,14,14,15];
new Chart("myChart", {
type: "line",
data: {
labels: xValues,
datasets: [{
backgroundColor: "rgba(0,0,0,1.0)",
borderColor: "rgba(0,0,0,0.1)",
data: yValues
}]
},
options:{...}
});
If you set the borderColor to zero, you can scatter plot the line graph:
borderColor: "rgba(0,0,0,0)",
Multiple Lines
Source Code
var xValues = [100,200,300,400,500,600,700,800,900,1000];
new Chart("myChart", {
type: "line",
data: {
labels: xValues,
datasets: [{
data: [860,1140,1060,1060,1070,1110,1330,2210,7830,2478],
borderColor: "red",
fill: false
},{
data: [1600,1700,1700,1900,2000,2700,4000,5000,6000,7000],
borderColor: "green",
fill: false
},{
data: [300,700,2000,5000,6000,4000,2000,1000,200,100],
borderColor: "blue",
fill: false
}]
},
options: {
legend: {display: false}
}
});
Linear Graphs
Source Code
var xValues = [];
var yValues = [];
generateData("x * 2 + 7", 0, 10, 0.5);
new Chart("myChart", {
type: "line",
data: {
labels: xValues,
datasets: [{
fill: false,
pointRadius: 1,
borderColor: "rgba(255,0,0,0.5)",
data: yValues
}]
},
options: {...}
});
function generateData(value, i1, i2, step = 1) {
for (let x = i1; x <= i2; x += step) {
yValues.push(eval(value));
xValues.push(x);
}
}
Function Graphs
Same as Linear Graph. Just change the generateData parameter(s):
generateData("Math.sin(x)", 0, 10, 0.5);
Bar Charts
Source Code
var xValues = ["Italy", "France", "Spain", "USA", "Argentina"];
var yValues = [55, 49, 44, 24, 15];
var barColors = ["red", "green","blue","orange","brown"];
new Chart("myChart", {
type: "bar",
data: {
labels: xValues,
datasets: [{
backgroundColor: barColors,
data: yValues
}]
},
options: {...}
});
Color Shades:
var barColors = [
"rgba(0,0,255,1.0)",
"rgba(0,0,255,0.8)",
"rgba(0,0,255,0.6)",
"rgba(0,0,255,0.4)",
"rgba(0,0,255,0.2)",
];
Horizontal Bars
Just change type from "bar" to "horizontalBar":
type: "horizontalBar",
Pie Charts
Example
new Chart("myChart", {
type: "pie",
data: {
labels: xValues,
datasets: [{
backgroundColor: barColors,
data: yValues
}]
},
options: {
title: {
display: true,
text: "World Wide Wine Production"
}
}
});
