parsing Unity YAML

parse.js

// for js-yaml 4.0, to avoid unity "YAML unknown tag" error: schema is required
import yaml from "js-yaml";
import path from "path";
import fs, { readFileSync } from "fs";

function parseAssetFile(p, assetsPath) {
  // Read the File
  let file = fs.readFileSync(path.resolve(assetsPath, p), { encoding: "utf-8" });

  // From github: https://github.com/nodeca/js-yaml/issues/100
  let types = {};

  // remove the unity tag line
  file = file.replace(/%TAG.+\r?\n?/, "");

  // replace each subsequent tag with the full line + map any types
  file = file.replace(/!u!([0-9]+).+/g, (match, p1) => {
    // create our mapping for this type
    if (!(p1 in types)) {
      const type = new yaml.Type(`tag:unity3d.com,2011:${p1}`, {
        kind: "mapping",
        construct: function (data) {
          return data || {}; // in case of empty node
        },
        instanceOf: Object,
      });
      types[p1] = type;
    }

    return `!<tag:unity3d.com,2011:${p1}>`;
  });

  // create our schema (migrate to 4.x sytnax)
  const schema = yaml.DEFAULT_SCHEMA.extend(Object.values(types));

  let doc = {};
  try {
    //using loadAll as it is a multi-file YAML, but the result will be in an Array
    doc = yaml.loadAll(file, null, { schema }); 
  } catch (e) {
    // handle the parsing error in your way, but doc will be empty if error occur.
  }
  return doc;
}