JavaScript Graphics
HTML Canvas
HTML Canvas is perfect for Scatter Plots
HTML Canvas is perfect for Line Graphs
HTML Canvas is perfect for combining Scatter and Lines
Scatter Plots
Source Code
const xArray = [50,60,70,80,90,100,110,120,130,140,150];
const yArray = [7,8,8,9,9,9,10,11,14,14,15];
// Plot Scatter
ctx.fillStyle = "red";
for (let i = 0; i < xArray.length-1; i++) {
let x = xArray[i]*400/150;
let y = yArray[i]*400/15;
ctx.beginPath();
ctx.ellipse(x, y, 2, 3, 0, 0, Math.PI * 2);
ctx.fill();
}
Line Graphs
Source Code
let xMax = canvas.height;
let slope = 1.2;
let intercept = 70;
// Plot Scatter
ctx.moveTo(0, intercept);
ctx.lineTo(xMax, f(xMax));
ctx.strokeStyle = "black";
ctx.stroke();
// Line Function
function f(x) {
return x * slope + intercept;
}
Combined
Source Code
let xMax = canvas.height;
let yMax = canvas.width;
let slope = 1.2;
let intercept = 70;
const xArray = [50,60,70,80,90,100,110,120,130,140,150];
const yArray = [7,8,8,9,9,9,10,11,14,14,15];
// Plot Scatter
ctx.fillStyle = "red";
for (let i = 0; i < xArray.length-1; i++) {
let x = xArray[i]*400/150;
let y = yArray[i]*400/15;
ctx.beginPath();
ctx.ellipse(x, y, 2, 3, 0, 0, Math.PI * 2);
ctx.fill();
}
// Plot Line
ctx.moveTo(0, intercept);
ctx.lineTo(xMax, f(xMax));
ctx.strokeStyle = "black";
ctx.stroke();
// Line Function
function f(x) {
return x * slope + intercept;
}
