Dominoes Valid Train Finder

Domino-train.js

/**
* Will find all permutations of the given set of 'dominos' that can
* be laid in a single line end to end to form a valid domino train.
*/
function start() {
  const dominos = ['05','60','54','66','40','43','21','35','03','24','32','52','11'];
  dominos.forEach(domino=>{
    let remaining = dominos.filter(d=>d!=domino);
    lookForValidTrain([domino], remaining);
  })
}

/**
 * @param {string[]} startingWith 
 * @param {string[]} remainingSet 
 */
function lookForValidTrain(startingWith, remainingSet){
  if(remainingSet.length == 0){
    console.log('valid train found:' + startingWith.join(', '));
  }else{
    const last = startingWith.slice(-1)[0];
    remainingSet.forEach(remainingDomino=>{
      if(last.substring(1) === remainingDomino.substring(0,1)){
        const newRemaining = remainingSet.filter((remaining)=>remaining!=remainingDomino);
        const newStarting = [...startingWith, remainingDomino];
        lookForValidTrain(newStarting, newRemaining);
      }
      
      //to check for matches using the other orientation
      //the first "if" is to prevent double dominos from creating two outputs (both their orientations are the same)
      if(remainingDomino.substring(1) !== remainingDomino.substring(0,1)){
        if(last.substring(1) === remainingDomino.substring(1)){
          const newRemaining = remainingSet.filter((remaining)=>remaining!=remainingDomino);
          const newStarting = [...startingWith, remainingDomino.substring(1) + remainingDomino.substring(0,1)];
          lookForValidTrain(newStarting, newRemaining);
        }
      }
    })
  }
}