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JS Canvas

HTML Canvas works well for Scatter Plot

HTML Canvas works well for Line Graph

HTML Canvas  works perfect for combining Scatter and Lines

Scatter Plots

Example

<!DOCTYPE html>

<html>

<body>

<canvas id=”myCanvas” width=”400″ height=”400″ style=”border:1px solid grey”></canvas>

<script>

const canvas = document.getElementById(“myCanvas”);

const ctx = canvas.getContext(“2d”);

canvas.height = canvas.width;

ctx.transform(1, 0, 0, -1, 0, canvas.height)

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];

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, 3, 3, 0, 0, Math.PI * 2);

  ctx.fill();

}

</script>

</body>

</html>

Output

js canvas

Line Graphs

Example

<!DOCTYPE html>

<html>

<body>

<canvas id=”myCanvas” width=”400″ height=”400″ style=”border:1px solid grey”></canvas>

<script>

const canvas = document.getElementById(“myCanvas”);

const ctx = canvas.getContext(“2d”);

ctx.fillStyle = “#FF0000”;

canvas.height = canvas.width;

ctx.transform(1, 0, 0, -1, 0, canvas.height)

let xMax = canvas.height;

let slope = 1.2;

let intercept = 70;

ctx.moveTo(0, intercept);

ctx.lineTo(xMax, f(xMax));

ctx.strokeStyle = “black”;

ctx.stroke();

function f(x) {

  return x * slope + intercept;

}

</script>

</body>

</html>

Output

line graph canvas js

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