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how to display form content after php processing

Im creating a forum for a little project of mine.
So far I have been able to get the form contents and use php to process (YES I HAVE NOT ACCOUNTED FOR SQL INJECTION).
Anyway, the php code is as follows:
test.php
<?php
if (isset($_POST["add"])){
// "Save Changes" clicked
$title = $_POST['title'];
$message = $_POST['message'];
$username = 'root';
$password = '';
$db = 'main_database';
$conn = mysqli_connect('localhost', $username , $password,$db);
if (!$conn){
die("unable to connect");
}
$dt = date('Y-m-d h:i:s');
$sql = "INSERT INTO threads (title,author,date_posted,post) VALUES ('$title', 2, '$dt', '$message')";
if (mysqli_query($conn, $sql)) {
echo "New record created successfully";
} else {
echo "Error: " . $sql . "<br>" . mysqli_error($conn);
}
mysqli_close($conn);
header('Location: http://127.0.0.1:5500/RuneScape_website/RS.com/aff/runescape/forums/ForumThread/~tm10CE.html');
}
?>
Now what I really want to do, is after this data has been saved to the database, I want to display the newly created blog comment to the direct page on load up. For example, When you click submit, the comment should appear in the directed html page.
The only way I think about it, is that I need either javascript to create a new attribute and append it to the list of existing attributes (e.g. ), or in the php create the div and use javascript/JQuery to access the php file and collect the html.
So I want the $title and $message to be used in the html page where its directed to.
A real example is like stack overflow. After I write an answer the page appends my response. This is what I want to achieve.
I'm curious how to go about this. Thanks :)

Don't you need to know which forum page this submitted comment belongs to?
If you add a column to threads table and store the name of the forum page in it (in this case: ~tm10CE.html), then from your html page, you can make an ajax call to a php file and include the name of the page as a querystring value. Inside the php file, query the threads table for the name of the page and return all the entries related to that page.

Manage confidential information in javascript

I have a table in my php that shows the data of a table in my database: username, email, etc. and I have also added an option to delete. The delete option works correctly and also shows a confirmation message with a necessary password before deleting.
I have the passwords saved in a table in the database but not encrypted.
The problem is that if a user explores the content of the page they can see what’s the password, so anyone can be able to delete data from the database. Therefore, a more or less skilled user can easily explore that content.
What can I do to prevent this from happening? Should I copy the same JavaScript code in another script and delete it from index.php? For more security, I tried to use a hash on the same index.php page but you can also see what the password is.
This is my code:
index.php
<table id="professorsRegistered" border="1px">
<tr>
<th colspan="3"><h2>Users</h2></th>
</tr>
<tr>
<th> Name </th>
<th> Email </th>
<th> Delete </th>
</tr>
<?php
$sql = "SELECT * FROM users"; /*Select from table name: users*/
$result = $conn->query($sql); /*Check connection*/
if ($result->num_rows==0){
echo "No users";
}else{
while($row = $result->fetch_assoc()) {
echo "<tr><td>".$row["username"]."</td><td>".$row["email"]."</td><td><a class='eliminate' onClick=\"getPass(".$row['id'].");\">X</a></td></tr>";
}
}
?>
</table>
<?php
$sql = "SELECT password FROM passwords WHERE passwords_id = '1';"; /*Select from table name: passwords*/
$result = $conn->query($sql); /*Check connection*/
$row = $result->fetch_assoc();
$password = $row["password"];
$hash = sha1($password);
/*echo "<p>".$hash."</p>";*/
?>
<script type = "text/javascript">
function getPass(user) {
var securePass = "<?php echo $password ?>";
var pass = prompt("Introduce password to delete: ", "Password");
if (pass!=securePass) {
return confirm('Incorrect Password');
}
else if (pass==securePass) {
window.location='delete.php?id='+user;
}
}
</script>
Delete.php
<?php
include('Conexion.php'); // Check connection
if (mysqli_connect_errno()) {
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
$id = $_GET['id']; // $id is defined
mysqli_query($conn,"DELETE FROM users WHERE id='".$id."'");
mysqli_close($conn);
header("Location: index.php");
?>

To make this more secure you should look at doing the following:
Ensure that the credentials are validated in the server-side code (PHP), not the client side code. As malicious user can very easily either edit the JavaScript or post data directly to your server and totally bypass your code.
Passwords should be hashed with a appropriate password hashing algorithm. SHA1 is not a good algorithm for password hashing as it is too fast, which makes brute force and dictionary attacks easier. A better choice would be something like bcrypt or pbkdf2 these are much slower making the above attacks much more difficult. You should also salt your password. This means just adding some randomness to the password before it is hashed. This will help prevent an attack known as a rainbow table attack in which an attacker uses a set of pre-hashed values and corresponding plain text to speed up the brute force process.
Do not build SQL query stings by string contactination as this leaves your application vulnerable to SQL injection attacks. If a malicious user was to send up 1' OR 1=1 -- as the id parameter then all the users would be deleted, this technique could also be used dump all of the data from the database or even delete the database altogether. Look in to using parameterized queries instead.
Luckily there is already loads of information on how to do this the right way. I would recommend looking at the OWASP website which has plenty of examples.

There are a couple of things which are very wrong about this design. You need to fix them.
Do not store cleartext passwords in your database. Hash passwords using a password hash function (like PHP's password_hash() or sodium_crypto_pwhash()) before storing them in the database. (SHA1 is not a password hash, and should not be used for this purpose.)
Do not construct SQL queries with string interpolation or concatenation. You're already using PDO, so you can easily use parameter placeholders to prevent SQL injection.
Do not expose password hashes to the browser in any form. If you need to verify a password, submit it to the server as part of the request to perform a password-protected action, so that a user cannot bypass the password check by typing a URL in manually.

PHP login algorithm not redirecting to next page (unsure on connection to database)

I am setting up a login page to take a users username and password then check that against a local database, however nothing is echoing form the database connection and there is no redirecting to the next page 'welcome.php' happening.
I have already tried many different ways of connecting to the local database and redirecting to different pages with different methods, none of which gave any error message or worked. using XAMPP Apache and mySQL modules to provide the local server.
<?php
if (isset($_POST['Login']))
{
$link = mysql_connect('localhost','root','password','budget');
if (!$link) {
die('Could not connect: ' . mysql_error());
}
echo 'Connected successfully';
session_start();
$username= $_POST['username'];
$password= sha1($_POST['password']);
$_SESSION['login_user']=$username;
$query = mysql_query("SELECT accounts.username, passwords.password_hash
FROM accounts
INNER JOIN passwords ON accounts.account_id = passwords.account_id
WHERE accounts.username = '$username' AND password_hash = '$password';");
if (mysql_num_rows($query) != 0){
?>
<script type="text/javascript">window.location.replace(welcome.php);
</script>;
<?php
mysql_close($link);
}
}
?>
I expect it to redirect to 'welcome.php' but instead it just refreshes the same page and nothing is echoed or given as an error

What isn't working?
Your JavaScript location.replace method needs a string as an input, you're not giving it that (as the input value is not quoted). It would be window.location.replace('welcome.php'); instead.
How to solve it?
The better solution is to redirect in PHP instead of in JavaScript, using header().
Additional remarks
I took the liberty of converting your code to use mysqli_ instead of the old, outdated and deprecated mysqli_ library. With this, you can use a prepared statement, as I have shown below. Use this approach for all your queries, bind the parameters through placeholders.
session_start();
if (isset($_POST['Login'])) {
$link = mysqli_connect('localhost','root','password','budget');
if ($link->connection_errno) {
die('Could not connect: ' . $con->error);
}
$username = $_POST['username'];
$password = sha1($_POST['password']);
$stmt = $link->prepare("SELECT a.username, p.password_hash
FROM accounts a
INNER JOIN passwords p
ON a.account_id = a.account_id
WHERE a.username = ?
AND p.password_hash = ?");
$stmt->bind_param("ss", $username, $password);
$stmt->bind_result($resultUsername, $resultPassword);
$stmt->execute();
if ($stmt->num_rows) {
$_SESSION['login_user'] = $username;
header("Location: welcome.php");
}
$stmt->close();
}
What's next?
Fix your passwords. Using sha1() is highly insecure for passwords, look into using passwords_hash()/password_verify() instead.

You need to add single quote around welcome.php
As welcome.php is neither a JavaScript keyword like this nor a number, single quote is mandatory also it is not a variable/object.
JS considers welcome as object and php as its method in welcome.php
Without it, a JavaScript error will be displayed:
ReferenceError: welcome is not defined
<script type="text/javascript">window.location.replace(welcome.php);
</script>
Also, there is no need of semi-colon ;.
JavaScript redirect without any condition.

What are the best practices for password submission? [closed]

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I am building a website with a user page. Currently it is set up in the following way:
The user types their username and password into corresponding fields then the user pressed submit.
The js code sends a get request to a php script with the password and username in plain text.
The php returns a randomly generated session token to the js code if the credentials are correct and an error message otherwise.
All future interactions the user engages in while logged on will now require the session token to be provided in any get requests. The php will then check that the session token is correct.
In the back end, the user name is stored in a database along side a salt and the hash (sha256) of the salted password. (the salt is randomly generated upon account creation).
My question is as follows: Is there anything in the description above that seems insecure? If so, what should be done instead. More broadly, what are the best practices around setting up a user login page or account system for a website. Thanks

Why are you trying to re-invent the wheel.
Php already has builting password encryption functions so why using Sha256 + Salt.
Again they are two type of authentication
1.) Session Based Login
2.) Token Based Login.
From your write-up you are combining session login with token login. You will need to decide which one that you want to apply.
Consequently they are alot of php validation or sanitization functions that you need to know to keep your code more secured.
1.) use strip_tags()
This will strips out all html elements from form inputs or variables
Eg
$email = strip_tags($_POST['email']);
2.) use htmlentities or htmlspecialchars to prevent XSS Attack.
This converts htmls tags to their respective entities. its only used when printing or echoing result to html page to
You will see how i used it in the welcome.php page
See Applications:
$email = htmlentities($_POST['email']);
3.) escaping variables against sql injection Attack
If you are using Mysqli, the best sql method to be used is prepared Statement.
Alternatively you can still escape variables using mysqli_real_escape_string() functions
See Application
// escape variables Against sql injections
$email = mysqli_real_escape_string($conn, $_POST['email']);
4.) If you are using session based login, You need to use sessionId regenerate method. This will help to regenerate new session
Id as user login thus preventing session fixation attack. do not worry you will need how to use it in the login.php code below
See Application:
// first you will need to initialize sessions
session_start();
session_regenerate_id();
This are just few among other security measures
Lets have a look at Session based login using php password verify functions
Assume this is your
registeration.php
<?php
$conn = mysqli_connect("localhost","root","","demo");
if(!$conn){
die("Connection error: " . mysqli_connect_error());
}
if(isset($_POST['submit'])){
$firstName = mysqli_real_escape_string($conn,$_POST['first_name']);
$surName = mysqli_real_escape_string($conn,$_POST['surname']);
$email = mysqli_real_escape_string($conn,$_POST['email']);
$password = mysqli_real_escape_string($conn,$_POST['password']);
$options = array("cost"=>4);
$hashPassword = password_hash($password,PASSWORD_BCRYPT,$options);
$sql = "insert into users (first_name, last_name,email, password) value('".$firstName."', '".$surName."', '".$email."','".$hashPassword."')";
$result = mysqli_query($conn, $sql);
if($result)
{
echo "Registration successfully";
}
}
?>
This is now how your login.php code will look like
<?php
$conn = mysqli_connect("localhost","root","","demo");
if(!$conn){
die("Connection error: " . mysqli_connect_error());
}
if(isset($_POST['submit'])){
$email = mysqli_real_escape_string($conn,$_POST['email']);
$password = mysqli_real_escape_string($conn,$_POST['password']);
$sql = "select * from users where email = '".$email."'";
$rs = mysqli_query($conn,$sql);
$numRows = mysqli_num_rows($rs);
if($numRows == 1){
$row = mysqli_fetch_assoc($rs);
if(password_verify($password,$row['password'])){
echo "Password verified and ok";
// initialize session if things where ok.
session_start();
session_regenerate_id();
$_SESSION['surname'] = $row['surname'];
$_SESSION['first_name'] = $row['first_name'];
$_SESSION['email'] = $row['email'];
// take me to welcome.php page
header('Location: welcome.php');
}
else{
echo "Wrong Password details";
}
}
else{
echo "User does not exist";
}
}
?>
Welcome.php will now look like code below to show authenticated users session info.
//use htmlentities or htmlspecialchars to prevent XSS Attack.
<?php echo htmlentities($_SESSION['surname'], ENT_QUOTES, "UTF-8"); ?>
<?php echo htmlspecialchars($_SESSION['first_name'], ENT_QUOTES, "UTF-8"); ?>
<?php echo htmlentities($_SESSION['email'], ENT_QUOTES, "UTF-8"); ?>
Now in your post I Saw where you wrote sending a generated token with every http request. In this case I guess you are
trying to mitigate CSRF Attack.
Here is the best and most secured way to do once you logged in
To prevent CSRF you'll want to validate a one-time token, POST'ed and associated with the current session.
Something like the following . . .
On the page where the user requests eg to insert a record for payments:
payment.php
<?php
session_start();
$token= md5(uniqid());
$_SESSION['payment_token']= $token;
session_write_close();
?>
<html>
<body>
<form method="post" action="payment_save.php">
<input type="hidden" name="token" value="<?php echo $token; ?>" />
Amount: <input type="hidden" name="token" value="100 usd" />
<input type="submit" value="submit" />
</form>
</body>
</html>
Then when it comes to actually inserting the record:
payment_save.php
<?php
session_start();
$token = $_SESSION['payment_token'];
unset($_SESSION['payment_token']);
session_write_close();
if ($token && $_POST['token']==$token) {
// Insert the record for payment
} else {
// log message. You are vulnerable to CSRF attack.
}
?>
The token should be hard to guess, unique for each insert request, accepted via $_POST only and expire after a few minutes
(expiration not shown in this illustrations).

How to have this form be validated on the same page?

Upon registering for an account for a subscription based product, I would like users to take a quiz. I want the results to be stored in a MySQL database. I've been using PHP and MySQL.
I have been able to have the quiz results and membership signup information sent to the database successfully, but verifying it is my issue because when the user goes back one page, then the quiz is reset.
For example, if a username is taken, the user is given an error and sent back to the quiz having to re-do the whole thing.
If there is a simple way to do it, I am interested in having javascript search the MySQL database for conditions such as if a username/email is already in use.
Right now, I have a javascript function that is called upon submitting the form. It currently only verifies that the two typed in passwords match each other. I would also it to call another function that searches that database and returns false if the username/email exists so that the user is not taken into another page.
This is how the code looks so far.
I am only experienced with very basic uses of php/MySQL. So my way of figuring this out was taking a free php/MySQL user system and modifying it to also insert results of the quiz into the table.
This is a common.php file that I include on each page.
'
// These variables define the connection information for your MySQL database
$username = "root";
$password = "*******";
$host = "localhost";
$dbname = "cc4u2";
// UTF-8 is a character encoding scheme that allows you to conveniently store
// a wide varienty of special characters, like ¢ or €, in your database.
// By passing the following $options array to the database connection code we
// are telling the MySQL server that we want to communicate with it using UTF-8
// See Wikipedia for more information on UTF-8:
// http://en.wikipedia.org/wiki/UTF-8
$options = array(PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES utf8');
// A try/catch statement is a common method of error handling in object oriented code.
// First, PHP executes the code within the try block. If at any time it encounters an
// error while executing that code, it stops immediately and jumps down to the
// catch block. For more detailed information on exceptions and try/catch blocks:
// http://us2.php.net/manual/en/language.exceptions.php
try
{
// This statement opens a connection to your database using the PDO library
// PDO is designed to provide a flexible interface between PHP and many
// different types of database servers. For more information on PDO:
// http://us2.php.net/manual/en/class.pdo.php
$db = new PDO("mysql:host={$host};dbname={$dbname};charset=utf8", $username, $password, $options);
}
catch(PDOException $ex)
{
// If an error occurs while opening a connection to your database, it will
// be trapped here. The script will output an error and stop executing.
// Note: On a production website, you should not output $ex->getMessage().
// It may provide an attacker with helpful information about your code
// (like your database username and password).
die("Failed to connect to the database: " . $ex->getMessage());
}
// This statement configures PDO to throw an exception when it encounters
// an error. This allows us to use try/catch blocks to trap database errors.
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
// This statement configures PDO to return database rows from your database using an associative
// array. This means the array will have string indexes, where the string value
// represents the name of the column in your database.
$db->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
// This block of code is used to undo magic quotes. Magic quotes are a terrible
// feature that was removed from PHP as of PHP 5.4. However, older installations
// of PHP may still have magic quotes enabled and this code is necessary to
// prevent them from causing problems. For more information on magic quotes:
// http://php.net/manual/en/security.magicquotes.php
if(function_exists('get_magic_quotes_gpc') && get_magic_quotes_gpc())
{
function undo_magic_quotes_gpc(&$array)
{
foreach($array as &$value)
{
if(is_array($value))
{
undo_magic_quotes_gpc($value);
}
else
{
$value = stripslashes($value);
}
}
}
undo_magic_quotes_gpc($_POST);
undo_magic_quotes_gpc($_GET);
undo_magic_quotes_gpc($_COOKIE);
}
// This tells the web browser that your content is encoded using UTF-8
// and that it should submit content back to you using UTF-8
header('Content-Type: text/html; charset=utf-8');
// This initializes a session. Sessions are used to store information about
// a visitor from one web page visit to the next. Unlike a cookie, the information is
// stored on the server-side and cannot be modified by the visitor. However,
// note that in most cases sessions do still use cookies and require the visitor
// to have cookies enabled. For more information about sessions:
// http://us.php.net/manual/en/book.session.php
session_start();
// Note that it is a good practice to NOT end your PHP files with a closing PHP tag.
// This prevents trailing newlines on the file from being included in your output,
// which can cause problems with redirecting users.
This is at the top of registration.php
// First we execute our common code to connection to the database and start the session
require("common.php");
// This if statement checks to determine whether the registration form has been submitted
// If it has, then the registration code is run, otherwise the form is displayed
if(!empty($_POST))
{
// Ensure that the user has entered a non-empty username
if(empty($_POST['username']))
{
// Note that die() is generally a terrible way of handling user errors
// like this. It is much better to display the error with the form
// and allow the user to correct their mistake. However, that is an
// exercise for you to implement yourself.
die("Please enter a username.");
}
// Ensure that the user has entered a non-empty password
if(empty($_POST['password']))
{
die("Please enter a password.");
}
// Make sure the user entered a valid E-Mail address
// filter_var is a useful PHP function for validating form input, see:
// http://us.php.net/manual/en/function.filter-var.php
// http://us.php.net/manual/en/filter.filters.php
if(!filter_var($_POST['email'], FILTER_VALIDATE_EMAIL))
{
die("Invalid E-Mail Address");
}
// We will use this SQL query to see whether the username entered by the
// user is already in use. A SELECT query is used to retrieve data from the database.
// :username is a special token, we will substitute a real value in its place when
// we execute the query.
$query = "
SELECT
1
FROM users
WHERE
username = :username
";
// This contains the definitions for any special tokens that we place in
// our SQL query. In this case, we are defining a value for the token
// :username. It is possible to insert $_POST['username'] directly into
// your $query string; however doing so is very insecure and opens your
// code up to SQL injection exploits. Using tokens prevents this.
// For more information on SQL injections, see Wikipedia:
// http://en.wikipedia.org/wiki/SQL_Injection
$query_params = array(
':username' => $_POST['username']
);
try
{
// These two statements run the query against your database table.
$stmt = $db->prepare($query);
$result = $stmt->execute($query_params);
}
catch(PDOException $ex)
{
// Note: On a production website, you should not output $ex->getMessage().
// It may provide an attacker with helpful information about your code.
die("Failed to run query: " . $ex->getMessage());
}
// The fetch() method returns an array representing the "next" row from
// the selected results, or false if there are no more rows to fetch.
$row = $stmt->fetch();
// If a row was returned, then we know a matching username was found in
// the database already and we should not allow the user to continue.
if($row)
{
die("This username is already in use");
}
// Now we perform the same type of check for the email address, in order
// to ensure that it is unique.
$query = "
SELECT
1
FROM users
WHERE
email = :email
";
$query_params = array(
':email' => $_POST['email']
);
try
{
$stmt = $db->prepare($query);
$result = $stmt->execute($query_params);
}
catch(PDOException $ex)
{
die("Failed to run query: " . $ex->getMessage());
}
$row = $stmt->fetch();
if($row)
{
die("This email address is already registered");
}
// An INSERT query is used to add new rows to a database table.
// Again, we are using special tokens (technically called parameters) to
// protect against SQL injection attacks.
$query = "
INSERT INTO users (
username,
password,
salt,
email,
style
) VALUES (
:username,
:password,
:salt,
:email,
:style
)
";
// A salt is randomly generated here to protect again brute force attacks
// and rainbow table attacks. The following statement generates a hex
// representation of an 8 byte salt. Representing this in hex provides
// no additional security, but makes it easier for humans to read.
// For more information:
// http://en.wikipedia.org/wiki/Salt_%28cryptography%29
// http://en.wikipedia.org/wiki/Brute-force_attack
// http://en.wikipedia.org/wiki/Rainbow_table
$salt = dechex(mt_rand(0, 2147483647)) . dechex(mt_rand(0, 2147483647));
// This hashes the password with the salt so that it can be stored securely
// in your database. The output of this next statement is a 64 byte hex
// string representing the 32 byte sha256 hash of the password. The original
// password cannot be recovered from the hash. For more information:
// http://en.wikipedia.org/wiki/Cryptographic_hash_function
$password = hash('sha256', $_POST['password'] . $salt);
// Next we hash the hash value 65536 more times. The purpose of this is to
// protect against brute force attacks. Now an attacker must compute the hash 65537
// times for each guess they make against a password, whereas if the password
// were hashed only once the attacker would have been able to make 65537 different
// guesses in the same amount of time instead of only one.
for($round = 0; $round < 65536; $round++)
{
$password = hash('sha256', $password . $salt);
}
// Here we prepare our tokens for insertion into the SQL query. We do not
// store the original password; only the hashed version of it. We do store
// the salt (in its plaintext form; this is not a security risk).
$query_params = array(
':username' => $_POST['username'],
':password' => $password,
':salt' => $salt,
':email' => $_POST['email'],
':style' => $_POST['style']
);
try
{
// Execute the query to create the user
$stmt = $db->prepare($query);
$result = $stmt->execute($query_params);
}
catch(PDOException $ex)
{
// Note: On a production website, you should not output $ex->getMessage().
// It may provide an attacker with helpful information about your code.
die("Failed to run query: " . $ex->getMessage());
}
// This redirects the user back to the login page after they register
header("Location: login.php");
// Calling die or exit after performing a redirect using the header function
// is critical. The rest of your PHP script will continue to execute and
// will be sent to the user if you do not die or exit.
die("Redirecting to login.php");
}
?>
This is the javascript code that checks that the two entered passwords match
function checkPassword() {
var pass1 = document.getElementById("pass").value;
var pass2 = document.getElementById("c_pass").value;
if (pass1 != pass2) {
alert("Your passwords do not match.");
return false;
}
document.getElementById("quizForm").method="post";
document.getElementById("quizForm").action="register.php";
}
And of course here is a bit of the html of the quiz. I just included one question for the sake of length since this is already a long post. This is located in registration.php below the php code.
<form id="quizForm">
<h2>Which Style?</h2>
Classy <input type="radio" name="style" value="Classy"><br>
Formal <input type="radio" name="style" value="Formal"><br>
Alternative <input type="radio" name="style" value="Alternative"><br>
Natural <input type="radio" name="style" value="Natural"><br>
Night Life <input type="radio" name="style" value="Nightlife"><br>
Businessman/Professional <input type="radio" name="style" value="Businessman/Professional"><br>
Hip/Vintage <input type="radio" name="style" value="Hip/Vintage"><br>
Seductive <input type="radio" name="style" value="Seductive"><br>
Athletic <input type="radio" name="style" value="Athletic"><br>
Worldly <input type="radio" name="style" value="Worldly"><br>
<br>
Username:<br />
<input type="text" name="username">
<br /><br />
E-Mail:<br />
<input type="text" name="email" value="emaiil" placeholder="Email" />
<br /><br />
Password:<br />
<input type="password" id="pass" name="password">
<br /><br />
Confirm Password:<br>
<input type="password" id="c_pass" name="password">
<input type="submit" onclick="return checkPassword();" value="Register" name="Submit">
</form>

JavaScript runs on clients computer, it cannot do anything like this.
But, there is an option that you send an ajax request to a php file which would verify the data and then echo the result back to browser.
For more about AJAX: http://www.w3schools.com/php/php_ajax_php.asp