How to go from one page to another page using javascript?

Question

From an admin page if the user is valid then the browser should go to another page.

When a user enters his user name and password, then clicks the OK button then another

Answer 1

Easier method is window.location.href = "http://example.com/new_url";

But what if you want to check if username and password whether empty or not using JavaScript and send it to the php to check whether user in the database. You can do this easily following this code.

html form -

javascript validation-

function validateForm(){
    var uname = document.forms["myForm"]["username"].value;
    var pass = document.forms["myForm"]["password"].value;

    if((!isEmpty(uname, "Log In")) && (!isEmpty(pass, "Password"))){

        return true;
    }else{
        return false;
    }
}

function isEmpty(elemValue, field){
    if((elemValue == "") || (elemValue == null)){
        alert("you can not have "+field+" field empty");
        return true;
    }else{
        return false;
    }
}

check if user in the database using php

";
    }

    $uname_tb = $_POST['username'];
    $pass_tb = $_POST['password'];

    $query ="SELECT * FROM user";
    $result = mysqli_query($con,$query);

    while($row = mysqli_fetch_array($result)){
        if(($row['username'] == $uname_tb) && ($row['password'] == $pass_tb)){
            echo "Login Successful";
            header('Location: dashbord.php');
            exit();
        }else{
            echo "You are not in our database".mysqli_connect_error();
        }
    }
    mysqli_close($con);
?>