// Get the text that the user has selected
const getSelectedText = () => window.getSelection().toString();
getSelectedText();

const getSubsets = arr => arr.reduce((prev, curr) => prev.concat(prev.map(k => k.concat(curr))), [[]]);

// Examples
getSubsets([1, 2]);     // [[], [1], [2], [1, 2]]
getSubsets([1, 2, 3]);  // [[], [1], [2], [1, 2], [3], [1, 3], [2, 3], [1, 2, 3]]

const primes = num => {
  let arr = Array.from({ length: num - 1 }).map((x, i) => i + 2),
    sqroot = Math.floor(Math.sqrt(num)),
    numsTillSqroot = Array.from({ length: sqroot - 1 }).map((x, i) => i + 2);
  numsTillSqroot.forEach(x => (arr = arr.filter(y => y % x !== 0 || y === x)));
  return arr;
};

primes(10); // [2, 3, 5, 7]

// Vanilla JS Solution:
var app = document.getElementById('app');

var typewriter = new Typewriter(app, { loop: true });

typewriter
    .typeString("I'm John and I'm a super cool web developer")
    .pauseFor(3000)
    .deleteChars(13) // "web developer" = 13 characters
    .typeString("person to talk with!") // Will display "I'm John and I'm a super cool person to talk with!"
    .start();

// React Solution:
import Typewriter from 'typewriter-effect';

<Typewriter
    options={{ loop: true }}
    onInit={typewriter => {
        typewriter
            .typeString("I'm John and I'm a super cool web developer")
            .pauseFor(3000)
            .deleteChars(13) // "web developer" = 13 characters
            .typeString("person to talk with!") // Will display "I'm John and I'm a super cool person to talk with!"
            .start();
    }}
/>

const jwt = require("jsonwebtoken");

const authToken = (req, res, next) => {
	const token = req.headers["x-auth-token"];

	try {
	req.user = jwt.verify(token, process.env.ACCESS_TOKEN_SECRET);

	next();
	} catch (err) {
	console.log(err.message);
	res.status(401).json({ msg: "Error authenticating token" });
	}
};

module.exports = authToken;

const binomialCoefficient = (n, k) => {
  if (Number.isNaN(n) || Number.isNaN(k)) return NaN;
  if (k < 0 || k > n) return 0;
  if (k === 0 || k === n) return 1;
  if (k === 1 || k === n - 1) return n;
  if (n - k < k) k = n - k;
  let res = n;
  for (let j = 2; j <= k; j++) res *= (n - j + 1) / j;
  return Math.round(res);
};

binomialCoefficient(8, 2); // 28