Example code generating a brownian motion SVG

brownian.js

/**
 * Author: Mitch Allen (https://mitchallen.com)
 * https://scriptable.com/
 */

var fs = require('fs');

function generate(limit) {

    let width = 1024
    let height = 512
    let margin = 10
    let maxMove = width * 0.10
    let x = width / 2
    let y = height / 2
    let precision = 0
    let path = "M"
    let backgroundColor = "gray"

    // generate the path

    for (let i = 0; i < limit; i++) {
        let distance = Math.random() * maxMove
        let angle = Math.random() * 360
        let tx = x + distance * Math.sin(Math.PI / 180 * angle);
        let ty = y + distance * Math.cos(Math.PI / 180 * angle);
        if (
            tx > margin && tx < (width - margin) &&
            ty > margin && ty < (height - margin)
        ) {
            x = +tx.toFixed(precision)
            y = +ty.toFixed(precision)
            path += `${x} ${y} `
        }    
    }

    // generate the svg markup

    let xmlns = "http://www.w3.org/2000/svg"

    let fd = `<svg viewBox="0 0 ${width} ${height}" xmlns="${xmlns}" width="${width}" height="${height}">\n`; 
    fd += `<rect fill="${backgroundColor}" width="${width}" height="${height}" />\n`
    fd += `<path fill="none" stroke="#000000" stroke-width="2" d="${path}" />\n`
    fd += '</svg>';

    // write the file

    var filename = 'brownian.svg';
    var stream = fs.createWriteStream(filename);
    stream.write(fd);
    stream.end();
    console.log(`Generated file: ${filename}` )
}

generate(2000)