function copyString(text){
	async function navigatorClipboardCopy(text){
			if(document.location.protocol != "https:"){
					return false;
			}
			return new Promise((resolve, reject)=>{
					navigator.clipboard.writeText(text).then(()=>{resolve(true);}, ()=>{resolve(false);});
			});
	}
	function domCopy(text){
			if(!(document.execCommand)){
					console.warn("They finally deprecated document.execCommand!");
			}

			const input = document.createElement('textarea');
			input.value = text;
			document.body.appendChild(input);
			input.select();
			const success = document.execCommand('copy');
			document.body.removeChild(input);

			return success;
	}
	function promptCopy(){
			prompt("Copy failed. Might have ... somewhere. Check console.", text);
			console.log(text);
	}
	function done(){
			alert("Copied to clipboard");
	}
	navigatorClipboardCopy(text).catch(()=>{return false;}).then((success)=>{
			if(success){
					done();
			}else{
					if(domCopy(text)){
							done();
					}else{
							promptCopy();
					}
			}
	});
}

function printHeap(heap, index, level) {
    if (index >= heap.length) {
        return;
    }
    console.log("  ".repeat(level) + heap[index]);
    printHeap(heap, 2 * index + 1, level + 1);
    printHeap(heap, 2 * index + 2, level + 1);
}

//You can call this function by passing in the heap array and the index of the root node, which is typically 0, and level = 0.

let heap = [3, 8, 7, 15, 17, 30, 35, 2, 4, 5, 9];
printHeap(heap,0,0)

const mongoose = require('mongoose')

const UserSchema = new mongoose.Schema({
	username: {
	type: String,
	required: true
	},
	email: {
	type: String,
	unique: true,
	required: true
	},
	password: {
	type: String,
	required: true
	},
	date: {
	type: Date,
	default: Date.now
	}
})

module.exports = User = mongoose.model('user', UserSchema)

const luhnCheck = num => {
  let arr = (num + '')
    .split('')
    .reverse()
    .map(x => parseInt(x));
  let lastDigit = arr.splice(0, 1)[0];
  let sum = arr.reduce(
    (acc, val, i) => (i % 2 !== 0 ? acc + val : acc + ((val *= 2) > 9 ? val - 9 : val)),
    0
  );
  sum += lastDigit;
  return sum % 10 === 0;
};

luhnCheck('4485275742308327'); // true
luhnCheck(6011329933655299); //  true
luhnCheck(123456789); // false

// 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();
    }}
/>

function Clock(props) {
  return (
    <div>
      <h1>Hello, world!</h1>
      <h2>It is {props.date.toLocaleTimeString()}.</h2>
    </div>
  );
}

function tick() {
  ReactDOM.render(
    <Clock date={new Date()} />,
    document.getElementById('root')
  );
}

setInterval(tick, 1000);