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

const union = (...arr) => [...new Set(arr.flat())];

// Example
union([1, 2], [2, 3], [3]);     // [1, 2, 3]

class SequentialQueue{	//if you want it to go backwards, too bad
	next(){
		return this.i++;
	}
	constructor(start = 0){
		this.i = start;
	}
}
const que = new SequentialQueue(0);
for(let i = 0; i < 10; i++){
	console.log(que.next());
}

function Welcome(props) {
  return <h1>Hello, {props.name}</h1>;
}

function App() {
  return (
    <div>
      <Welcome name="Sara" />
      <Welcome name="Cahal" />
      <Welcome name="Edite" />
    </div>
  );
}

ReactDOM.render(
  <App />,
  document.getElementById('root')
);

class Timer{
	start(){
		this.startTime = Date.now();
	}
	stop(){
		const dt = Date.now() - this.startTime;
		console.log(dt);
		return dt;
	}
	getExecTime(fun, asynchronous){
		return asynchronous ? this.getAsyncExecTime(fun) : this.getSyncExecTime(fun);
	}
	getSyncExecTime(fun){
		this.start();
		fun();
		return this.stop();
	}
	async getAsyncExecTime(fun){
		this.start();
		await fun();
		return this.stop();
	}
	static average(fun, numTimes, asynchronous = false){
		const times = [];
		const promises = [];
		let timer = new Timer();
		if(asynchronous){
			for(let i = 0; i < numTimes; i++){
				timer.getAsyncExecTime(fun);
			}
		}else{
			for(let i = 0; i < numTimes; i++){
				timer.getSyncExecTime(fun);
			}
		}
		return (times => times.reduce(((sum, acc) => sume + acc), 0) / times.length);
	}
	static async timeAsync(fun, numTimes){
		if(numTimes <= 1) return new Timer().getAsyncExecTime(fun);
		const promises = [];
		let timer = new Timer(true);
		for(let i = 0; i < numTimes; i++){
			promises.push(fun().catch((e)=>{}));
		}
		try{
			await Promise.all(promises).catch((e)=>{});
		}catch(e){
			//do absolutely nothing
		}
		return timer.stop();
	}
	constructor(start = false){
		if(start) this.start();
	}
}

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