node-canvas-p5js-instance-mode.js

const w = 400, h = 400
setupWindow(w, h)

const p5 = require("p5")

new p5(p => {
  // Declare sketch variables here
  p.setup = () => {
    p.createCanvas(w, h)
    // setup function
    saveAsPNG(p, "name") // will not run draw
  }
  // p.draw = () => {
  //   // draw function
  // }
})

async function saveAsPNG(p5Inst, filename = "sketch", exit = true) {
  const fs = require("fs");
  const buffer = p5Inst._renderer.drawingContext.canvas.toBuffer()
  await fs.promises.writeFile(filename + ".png", buffer)
  if (exit) process.exit(0)
}

function setupWindow(w = 100, h = 100) {
  const { createCanvas } = require("canvas");
  const { JSDOM } = require("jsdom")

  global.window = global

  const dom = new JSDOM()
  global.document = dom.window.document

  const nodeCanvas = createCanvas(w, h)

  dom.window.HTMLCanvasElement.prototype.getContext = (type) => {
    return nodeCanvas.getContext(type)
  };

  const { performance } = require("perf_hooks")
  global.performance = performance

  global.screen = {}

  global.addEventListener = dom.window.addEventListener.bind(dom.window)
  global.removeEventListener = dom.window.removeEventListener.bind(dom.window)

  global.navigator = { userAgent: "node" }
}