Связывание двух страниц

function login() {
  var myOut = document.getElementById("output");

  var users = ["admin1", "admin2", "admin3", "admin4"];
  var pass = ["pass1", "pass2", "pass3", "pass4"];

  var aUser = document.getElementById("user_name").value;
  var aPass = document.getElementById("password").value;

  for (i = 0; i < users.length; i++) {
    if (users[i] == aUser && pass[i] == aPass) {
      myOut.innerHTML = "Correct - you will be redirected";
      setTimeout(function() {
        window.location = "dashboard.php";
      },1000);  
      return;
    }
  }
  myOut.innerHTML = "Who Are You? / Incorrect Password";
  myOut.className = "error";
}


function init() {
  var login_button = document.getElementById("login_button");
  if (login_button !== null) {
    login_button.onclick = login;
  }

  var register_button = document.getElementById("register_button");
  if (register_button !== null) {
    register_button.onclick = validation;
  }

  for (i = 1; i <= 10; i++) {
    var myErr = document.getElementById("err" + i);
    if (myErr !== null) {
      myErr.className = "error";
    }
  }
}
function validation() { /* you need some code here */ }
window.onload=init;

<h1>
  Please Login
</h1>
<form id = "order_form">
  <fieldset>
    <legend>Login</legend>
    <div class = "tab">
      <div class = "tRow">
        <div class = "tRow">
          <div class = "tCell">
            <label for = "user_name">User Name:</label>
          </div>
          <div class = "tCell">
            <input type = "text" id = "user_name" maxlength = "50" />
          </div>
        </div>
        <!-- END OF THIS SELECTION -->
        <div class = "tRow&gt; &lt;div class = ">
          <label for = "password">Password:</label>
        </div>
        <div class = "tCell">
          <input type = "text" id = "password" required = "" maxlength = "50" />
        </div>
      </div>
      <!-- END OF THIS SELECTION -->
      <div class = "tRow">
        <div class = "tCell">
          &nbsp;
        </div>
        <div class = "tCell">
          <input type = "button" id = "login_button" value = "Login" />
        </div>

      </div>
      <!--END OF THIS SELECTION-->
      <div class = "tRow">
        <div class = "tCell">
          &nbsp;
        </div>
        <div class = "tCell">
          <input type = "button" id = "register_button" value = "Register Now!" />
        </div>

      </div>
      <!--END OF THIS SELECTION-->
    </div>
    <!-- END OF THE TABLE  -->
    <br />
    <div id = "output" class = "error"></div>
  </fieldset>
</form>