Laravel Mix in Express (node) apps

app.js

const path = require('path');
const { mixFn } = require('./mix');

// mixFn will parse and store the manifest file internally
// it returns a new 
const mix = mixFn(path.join(__dirname, 'public')); // where laravel-mix generates the manifest and hot files

console.log(mix('/css/app.css')); // /css/app.css?id=2995d68b12d2d1326355
console.log(mix('/js/js.css')); // /js/app.js?id=87e01f645f82f2f01ab3

mix.js

// This is a typescript file. You can convert it to javascript online
import * as fs from 'fs';

/**
 * Creates a new mix handler
 *
 * @param rootPath
 * @param manifestDirectory
 * @returns {Function}
 */
export const mixFn = (
  rootPath: string,
  manifestDirectory: string = '',
): ((path: string) => string) => {
  const publicDir = '/public';

  if (manifestDirectory.length > 0 && !manifestDirectory.startsWith('/')) {
    manifestDirectory = `/${manifestDirectory}`;
  }

  const manifestPath = `${rootPath}${publicDir}${manifestDirectory}/mix-manifest.json`;
  const isHot: boolean = fs.existsSync(`${rootPath}${publicDir}${manifestDirectory}/hot`);

  if (!fs.existsSync(manifestPath)) {
    throw new Error(`Cannot find manifest file at ${manifestPath}`);
  }

  const manifest: any = JSON.parse(fs.readFileSync(manifestPath, 'utf8'));

  return (path: string): string => {
    if (!path.startsWith('/')) {
      path = `/${path}`;
    }

    if (!manifest[path]) {
      throw new Error(
        `Unable to locate Mix file: ${path}. Please check your webpack.mix.js output paths and try again.`,
      );
    }

    return isHot
      ? `http://localhost:8080${manifest[path]}`
      : `${manifestDirectory}${manifest[path]}`;
  };
};