backtracking-loop.ts

const args = [
  [1,2,3],
  [1],
  ['a', 'b'],
  ['c', 'd', 'e'],
  [5],
];

const r = [[]] as any;
let i = 0;
while (i++ !== args.length) {
  const s = [];
  while (r.length) {
    const t = r.shift();
    if (t.length < args.length) {
      args[t.length].map(i => s.push([...t, i]));
    }
  }
  r.push(...s);
}
console.log(r)