Return value from php to javascript

Question

I writing a registration/login form, I am sending user info via POST to a PHP that is looking in a DB. I would like that the PHP returns an ok or wrong value to the js and I don't now how to do it. Here my js:

 ui.onClick_regsubmit=function()
{
var fname=document.getElementById('fname').value;
var lname=document.getElementById('lname').value;
var password=document.getElementById('password').value;
var mail=document.getElementById('mail').value;
var affiliation=document.getElementById('affiliation').value;
var data = new FormData();
var xhr = (window.XMLHttpRequest) ? new XMLHttpRequest() : new activeXObject("Microsoft.XMLHTTP");
data.append("fname",fname);
data.append("lname",lname);
data.append("password",password);
data.append("mail",mail);
data.append("affiliation",affiliation);
xhr.open( 'post', 'PHP/registration.php', false );
xhr.send(data);
window.alert(affiliation);
}

And the php:

<?php
 mysql_connect('localhost','root','') or die('Cannot connect mysql server');
 mysql_select_db('ChemAlive_login') or die('cannot connect database');
 $lname=$_POST['lname'];
 $fname=$_POST['fname'];
 $password=$_POST['password'];
 $mail=$_POST['mail'];
 $affiliation=$_POST['affiliation'];
 $q=mysql_query("select * from login where mail='".$mail."' ") or die(mysql_error());
 $n=mysql_fetch_row($q);
 if($n>0)
{
 $q=mysql_query("select password from login where mail='".$mail."' ");
 $pp=mysql_fetch_row($q);
 if($pp[0]=$password) echo "ok";
 else echo "wrong";
}
else
{ $insert=mysql_query("insert into login values('".$fname."','".$lname."','".$mail."','".$password."','".$affiliation."')") or die(mysql_error());}
?>

I would like to return to js this ok or wrong value. How to do it?

Answer 1

xhr.onload=function()
{
 if (xhr.status==200) 
 {
 alert(xhr.response);
 }else
 {
 alert("unknown server error");
 }
}

it will be better if the server sends a response code, and javascript will transfer this code to the text. For example:

onload=function()
{
 switch(xhr.response)
 {
 case "0":{alert("unknown error")};break;
 case "1":{alert("email is already used")};break;
 ...
 }
}

I think thought it is clear

Answer 2

I do not have the rep to comment or I'd ask for details, but if you can consider using ajax, it could look something like this:

php:

$doit = //your query;
if($doit){
$youdid = 'ok';
}
else{
exit('1');
}

js:

$(document).ready(function () {
 var foo = $("#formfield")val();
 $.ajax({
 "foo":foo;
 type: 'POST',
 url: 'some.php',
 success: function(responseText) { 
if(responseText == "1") {
alert("Leave instantly");
};
}
else {
alert("One of us");
}

Answer 3

If you want to return either ok or wrong to the JavaScript to handle you could do something like this in your registration.php page:

 $q=mysql_query("select password from login where mail='".$mail."' ");
 $pp=mysql_fetch_row($q);
 if($pp[0]=$password){ 
 header('Content-Type: application/json');
 echo json_encode(array('password' => 'ok'));
 }else{ 
 header('Content-Type: application/json');
 echo json_encode(array('password' => 'wrong'));
 }

I have not fully testing this, but the idea is to set the header to return json and then send it a JSON string.

Does that make sense?

Like I said in my comment below I have only used jQuery for AJAX. But here is a little something of what I know about XMLHttpRequest and my undertsanding of how you would test what you get back.

You can set up a listener for when you get a response back onreadystatechange and then put the response in a variable var pass = xhr.response and then just output the text to an alert box like alert(pass.password).

if (xhr.onreadystatechange === 4 && xhr.status === 200){
 var pass = xhr.response;
 //should output either ok or wrong
 alert(pass.password);
}

Read more about XMLHttpRequest here

Let me know if that works.

• Laetis: How shoud I modify the js too test this json array password?
• nothing123456: Well to be honest I have only ever made an AJAX request using jQuery and the $.ajax method. This method gives you the ability to run a function on success, failure, and/or completion. Using this method a way to test it would be success: function (json) { alert(json.password); }, I could put an example of a full jQuery ajax request if that would be helpful? api.jquery.com/jquery.ajax