This script removes all entries in the unity asset file that are not needed internally

gc-entries-in-asset,ts

#!/usr/bin/env node

/*
 * This script removes all entries in the asset file that are not needed.
 * Please note that this doesn't consider external references.
 */

const fs = require('fs');

const path = process.argv[2];

const data = fs.readFileSync(path, 'utf8');

const split = data.split(/(?<=\n)(?=---)/g);

const heading = split[0];
const body = split.slice(1).map(parseBody);

const map = new Map(body.map(x => [x.id, x]));

const queue = body.filter(x => x.need).map(x => x.id);

while (queue.length) {
    const id = queue.shift();
    const entry = map.get(id);
    entry.dependencies.forEach(dep => {
        const depEntry = map.get(dep);
        if (!depEntry.need) {
            depEntry.need = true;
            queue.push(dep);
        }
    });
}

const result = heading + body.filter(x => x.need).map(x => x.body).join('');

fs.writeFileSync(path, result, 'utf8');

/**
 * 
 * @param {string} part
 */
function parseBody(body) {
    const matched = body.match(/^--- .*&(-?\d+)/);
    const dependenciesList = [...body.matchAll(/\{fileID: (-?\d+)\}/g)].map(match => match[1]);
    const dependencies = [...new Set(dependenciesList.filter(x => x != '0'))];
    const need = /m_ObjectHideFlags: 0/.test(body);
    return {
        id: matched[1],
        body,
        dependencies,
        need,
    }
}