createJSON.js

const { Omnibus } = require("omnibus-rxjs");
const fs = require("fs");
const { join } = require("path");
const bus = new Omnibus();
bus.spy(({ type, payload }) => console.log(type, payload));

const dirPath = "./";

const jsonMaker = bus.filter(
  ({ type }) => type === "png",
  ({ payload: { idx } }) => {
    const pngFile = `${idx}.png`;
    const jsonFile = `${idx}.json`;

    const jsonObj = {
      name: `My Numbered NFT: ${idx}`,
      image: pngFile,
      attributes: [
        { trait_type: "Layer-1", value: "0" },
        { trait_type: "Layer-2", value: "0" },
        { trait_type: "Layer-3", value: "0" },
        { trait_type: "Layer-4", value: "1" },
      ],
      properties: {
        files: [{ uri: pngFile, type: "image/png" }],
      },
      collection: { name: "numbers", family: "numbers" },
    };

    fs.writeFileSync(join(dirPath, jsonFile), JSON.stringify(jsonObj, null, 2));
  }
);

const files = fs.readdirSync(dirPath);
for (const file of files) {
  if (file.endsWith(".png")) {
    const idx = Number(file.replace(".png", ""));
    bus.trigger({ type: "png", payload: { idx } });
  }
}