addPlayers.js

let counter = 0;
let form = document.getElementById("form");

let playerList = [];

function addInput() {
  counter++;
  let input = document.createElement("input");
  input.placeholder = "Player name";
  input.id = "playerInput" + counter;
  input.className = "player-input";
  input.addEventListener("keydown", (event) => {
    // when a keyDown event is detected
    if (event.key == "Enter") {
      // and IF that key is 'Enter'
      event.preventDefault(); // prevent default page reload
      addInput(); // run addInput again to add an input below
    }
  });
  form.appendChild(input);
  input.focus();
  document.getElementById("start").disabled = false;
}

function startGame() {
  let list = form.children;
  for (let i = 0; i < list.length; i++) {
    let input = document.getElementById(list[i].id).value;
    playerList.push(input);
  }
}

function go() {
  let params = new URLSearchParams();
  params.append("playerList", JSON.stringify(playerList));
  let url = "game.html?" + params.toString();
  location.replace(url);
}