You can use jsdom to simulate browser environments and natively run Snap.svg in Node.js.
Example:
const jsdom = require('jsdom');
const xmlserializer = require('xmlserializer');
jsdom.env('', [require.resolve('snapsvg')], (error, window) => {
if (error) throw error;
const paper = window.Snap(100, 100);
const rect = paper.rect(20, 20, 60, 60);
rect.attr({fill: 'red'});
const svg = xmlserializer.serializeToString(paper.node);
window.close();
console.log(svg);
});
Prints:
<svg height="100" version="1.1" width="100" xmlns="http://www.w3.org/2000/svg"><desc>Created with Snap</desc><defs/><rect x="20" y="20" width="60" height="60" style="" fill="#ff0000"/></svg>