HTML Canvas
HTML Canvas 非常適合散點圖
HTML Canvas 非常適合折線圖
HTML Canvas 非常適合結合散點和線條
散點圖
原始碼
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];
// 繪製散點圖
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();
}
折線圖
原始碼
let xMax = canvas.height;
let slope = 1.2;
let intercept = 70;
// 繪製散點圖
ctx.moveTo(0, intercept);
ctx.lineTo(xMax, f(xMax));
ctx.strokeStyle = "black";
ctx.stroke();
// 線條函式
function f(x) {
return x * slope + intercept;
}
組合
原始碼
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];
// 繪製散點圖
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();
}
// 繪製線條
ctx.moveTo(0, intercept);
ctx.lineTo(xMax, f(xMax));
ctx.strokeStyle = "black";
ctx.stroke();
// 線條函式
function f(x) {
return x * slope + intercept;
}
