Form doesn't save data into mySQL tables

Question

I'm using mySQL, javascript and php. I have a form in my website to register new users into it. It's connected to a users table in my mySQL where it saves the users data.

The thing is I can't apply the javascript constraints to the field forms unless I have event.preventDefault();, it will just connect to my php page no matter what and save the data into my table.
But if I use the event.preventDefault(); it will apply the constraints but when I fill it correctly and click register it won't save anything, just creates an empty user in mysql table.

How can I solve this?

var constraints = {
  email: {
    email: true,
    presence: true,
  },
  Telefone: {
    presence:true,
    format: {
      pattern: "[+0-9]+",
      message: "apenas pode conter números [0-9]"
    }
  },
  pwd: {
    presence: true,
    length: {
      minimum: 5
    }
  },
  cpwd: {
    presence: true,
    equality: {
      attribute: "pwd",
      message: "as passwords não coincidem"
    }
  }
}


  $("#validationForm").submit(function(event){

     event.preventDefault();

  $("#error").html("");

  console.log(event);

  var errors = validate($("#validationForm"), constraints);

  if (errors) {
    $("#submited").html("");
    for (var key in errors) {
      $("#error").append(errors[key] + "<br />");
      $("#" + key).css("border","1px red solid");
    }       
  }else {
    // $("#submited").html("Form Submited");

    // redirect to php
     window.location.href="registar.php";
  }
});

Answer 1

That's because you are manually redirecting to your PHP page.

Instead of this line:

window.location.href="registar.php";

You should rather

document.getElementById("form_to_submit").submit();