How can I generate an array of sentences based on the array of words using JS?

let result = [
  ["Training für die Polizei"],
  ["Training für die Polizisten"],
  ["Training für die Militär"],
  ["Training für das Polizei"],
  ["Training für das Polizisten"],
  ["Training für das Militär"],
  ["Trainings für die Polizei"],
  ["Trainings für die Polizisten"],
  ["Trainings für die Militär"],
  ["Trainings für das Polizei"],
  ["Trainings für das Polizisten"],
  ...
]

<pre>let ar = [
  ["Training", "für", "die", "Polizei"],
  ["Trainings", "", "das", "Polizisten"],
  ["Trainingseinheit", "", "", "Militär"]
]

let indexes = [0, 1, 2, 3]; //The order and length may change
let separators = [' ', ' ', ' ', ' '];
let result = [];
ar = ar.map(x => indexes.map(e => x.slice()[0] = x[e]));
for (let row = 0; row < ar.length; row++) {
  let word = ar[row][0];
  
  for (let col = 1; col <= ar[row].length - 1; col++) {
    const colLength = ar.map(e => e[col]).filter(e => e != '').length
    let sentence = [];

    for (let val = 0; val <= colLength; val++) {
      let words = ar[val];
      if (words != '') {
        sentence.push(words)
      }
    }
    result.push(sentence)
  }
}
console.log(result)