anagrams.js

function permute(xs) {  
  function p(xs, prefix) {
    if (!xs.length) return prefix;
    else {
      let results = [];
      for (let i = 0; i < xs.length; i++) {
        let rem = xs.slice(0, i) + xs.slice(i+1);
        results = results.concat(p(rem, prefix + xs[i]));
      }
      return results;
    }
  }
  return p(xs, "");
}

let isAnagram = (_) => Math.round(Math.random());

let anagrams = ["abc", "car", "bus"]
  .map(permute)
  .reduce((b, a) => isAnagram(a) ? b.concat(a) : b, []);

console.log(anagrams);