.gitignore

/node_modules

index.js

#!/usr/bin/env node

const _ = require('lodash');

/** 
 * Recursive version of fibonacci using memoize technique and lodash.
 */
const fibonacci = _.memoize((n) => (
  n <= 1 ? Math.max(0, n) : fibonacci(n - 1) + fibonacci(n - 2)
));

if (require.main == module) {
  const n = process.argv[2];
  if (n === undefined) {
    console.error(`${process.argv[0]} ${process.argv[0]} <number>`);
    process.exit(1);
  }
  if (n < 0) {
    console.error(`Enter a positive number.`);
    process.exit(1);
  }

  const val = fibonacci(n);
  console.info(`Fibonacci digit @ ${n}: ${val}`);
}

package-lock.json

{
  "name": "ngx-demo",
  "version": "1.0.0",
  "lockfileVersion": 1,
  "requires": true,
  "dependencies": {
    "lodash": {
      "version": "4.17.5",
      "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.5.tgz",
      "integrity": "sha512-svL3uiZf1RwhH+cWrfZn3A4+U58wbP0tGVTLQPbjplZxZ8ROD9VLuNgsRniTlLe7OlSqR79RUehXgpBW/s0IQw=="
    }
  }
}

package.json

{
  "name": "npx-demo",
  "version": "1.0.2",
  "description": "",
  "main": "index.js",
  "bin": "index.js",
  "repository": {
    "url": "https://gist.github.com/zurfyx/47cf03423d2349ab5dbfab7ccc56adc6"
  },
  "dependencies": {
    "lodash": "^4.17.5"
  },
  "devDependencies": {},
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC"
}