Commit b21627c

<!DOCTYPE html>

<html lang="en">

<head>

<meta charset="UTF-8">

<title>HTML5 Canvas</title>

</head>

<body>

<canvas id="draw" width="800" height="800"></canvas>

<script>

const canvas = document.querySelector('#draw');

const ctx = canvas.getContext('2d');

canvas.height = window.innerHeight;

canvas.width = window.innerWidth;

ctx.strokeStyle = '#BADASS';

ctx.lineJoin = 'round';

ctx.lineCap = 'round';

ctx.lineWidth = 60;

let isDrawing = false;

let lastX = 0;

let lastY = 0;

let hue = 0;

let direction = true;

function draw(e) {

if(!isDrawing) return;

ctx.strokeStyle = `hsl(${hue}, 100%, 50%)`;

ctx.beginPath();

ctx.moveTo(lastX,lastY);

ctx.lineTo(e.offsetX, e.offsetY);

ctx.stroke();

[lastX, lastY] = [e.offsetX, e.offsetY];

hue++;

if( hue >= 360) {

hue = 0;

}

if (ctx.lineWidth >= 100 || ctx.lineWidth <= 1) {

direction = !direction;

}

if (direction) {

ctx.lineWidth++;

} else {

ctx.lineWidth--;

}

}

canvas.addEventListener('mousedown', (event) => {

isDrawing = true;

[lastX, lastY] = [event.offsetX, event.offsetY];

});

canvas.addEventListener('mousemove', draw);

canvas.addEventListener('mouseup', () => isDrawing = false);

canvas.addEventListener('mouseout', () => isDrawing = false);

</script>

<style>

html, body {

margin:0;

}

</style>

</body>

</html>