https://adrianmejia.com/most-popular-algorithms-time-complexity-every-programmer-should-know-free-online-tutorial-course/#Has-duplicates

has-duplicates.js

function hasDuplicates(n) {
  const duplicates = [];

  for (let outter = 0; outter < n.length; outter++) {
    for (let inner = 0; inner < n.length; inner++) {
      if(outter === inner) continue;

      if(n[outter] === n[inner]) {
        return true;
      }
    }
  }
  
  return false;
}