js-simple-mangler/dist/index.js

A simple JavaScript mangler that works across multiple files.

/* IMPORT */
import fs from 'node:fs';
import path from 'node:path';
import process from 'node:process';
import { parseArgv } from 'specialist';
import readdir from 'tiny-readdir';
/* HELPERS */
const Helpers = {
    /* API */
    getOptions: () => {
        const { folder, ext, props } = parseArgv(process.argv);
        const root = path.resolve(process.cwd(), folder);
        const propsRe = new RegExp(`(?<!\\w|\\/\\S*)(${props.replaceAll(',', '|')})(?!\\w)`, 'g');
        const options = { ext, root, propsRe };
        return options;
    },
    getMangled: (() => {
        const cache = {};
        let index = 0;
        const getIdentifier = () => {
            const identifier = (index++).toString(32).toUpperCase();
            if (/^[a-z0-9]/.test(identifier))
                return getIdentifier(); // Skipping identifiers starting with a number (invalid) or with a lower case character (high probability of collision)
            return identifier;
        };
        const getIdentifierProp = (prop) => {
            return cache[prop] || (cache[prop] = getIdentifier());
        };
        return getIdentifierProp;
    })(),
    getSources: async () => {
        const { ext, root } = Helpers.getOptions();
        const { files } = await readdir(root, { followSymlinks: false });
        const sourceRe = /\.(js|jsx|ts|tsx)$/;
        const isSource = (file) => sourceRe.test(file) && (!ext || file.endsWith(ext));
        const sources = files.filter(isSource);
        return sources;
    }
};
/* MAIN */
const Mangler = {
    /* API */
    mangle: async () => {
        const { propsRe } = Helpers.getOptions();
        const sources = await Helpers.getSources();
        let bytesPrev = 0;
        let bytesNext = 0;
        for (const source of sources) {
            const contentPrev = fs.readFileSync(source, 'utf8');
            const contentNext = contentPrev.replace(propsRe, Helpers.getMangled);
            bytesPrev += contentPrev.length;
            bytesNext += contentNext.length;
            fs.writeFileSync(source, contentNext);
        }
        console.log(`Total bytes: ${bytesPrev} -> ${bytesNext}`);
    }
};
/* EXPORT */
export default Mangler;