PHP reloading scripts without reloading the page

**bokeh** · 06-05-2009 06:34 AM

Originally Posted by Mindzai

Who said screen resolution is an issue? It's stats software. Analytics captures client screen resolution...

So why does he want an iframe?

**Mindzai** · 06-05-2009 06:46 AM

Because he was given the (extremely bad) advice that he should not use AJAX to send the stats back to the server. If you read the very first line of first post:

I'm writing Analytical software that uses javascript but mainly PHP to log things

**Ronnie268** · 06-05-2009 10:46 AM

Originally Posted by bokeh

If you wrote your html and css properly you wouldn't need to worry about the client's screen dimensions. What are you going to do for people with javascript disabled.

If you'll excuse me saying, I'm a web designer and I think I know how to write CSS and (X)HTML. As Mindzai correctly pointed out, I am writing an analytics package for distribution (free) and, although this is not something I require, Screen Resolution is something logged by Google Analytics, the most well-known free package. Many people may take this into account when considering using my software.

For people without javascript, the main script runs in php, so that will pick most things up. Please do not flame, it is considered offensive on forums. The iframe was a temporary method of implementing javascript.

To connect javascript and PHP, it is necessary either to set cookies or to compose a url using javascript. Both require a page reload for PHP to interpret them. This messes up detection of the referrer in PHP, so I used an iframe.

I repeat on sending a url of a PHP script for the image, how do I get it do display the image?

Thanks,

Ronnie268

**Mindzai** · 06-05-2009 12:11 PM

Originally Posted by Ronnie268

To connect javascript and PHP, it is necessary either to set cookies or to compose a url using javascript. Both require a page reload for PHP to interpret them. This messes up detection of the referrer in PHP, so I used an iframe.

This is not correct. As Ive said a few times in this thread now, the right way to do this is to send a post request via AJAX. This doesn't require composing a url with javascript, setting cookies or reloading any pages.

if you really want to use an image (which I would consider a "bodge job" as we say in the UK), you'd have to set the appropriate HTTP header withthe header() function, and then output the image file to the browser.

PHP Code:


<?php

header('Content-type: image/gif');

readfile('file.gif');

exit();

?>

I really would not suggest doing this though, it's not a good approach.

**Ronnie268** · 06-06-2009 05:02 PM

Originally Posted by Mindzai

if you really want to use an image (which I would consider a "bodge job" as we say in the UK), you'd have to set the appropriate HTTP header withthe header() function, and then output the image file to the browser.

Yes - I'm UK too. I am aware of this being a "bodge" job.

Thanks for the Ajax solution. How exactly would I do this? I'm not an Ajax guy!

Thanks,

Ronnie268

**bokeh** · 06-07-2009 04:09 AM

Originally Posted by Ronnie268

How exactly would I do this? I'm not an Ajax guy!

Here's a really simple example. The Javascript alerts are only there so you can see what's happening.

http://bokehman.com/ajax.stats.capture/

index.php

HTML Code:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
   "http://www.w3.org/TR/html4/strict.dtd">

<html>
<head>

<script src="./stats_capture.js" type="text/javascript"></script>

<title>Stats capture</title>
</head>
<body>

<p>
Stats capture test
</p>

</body>
</html>

stats_capture.js

HTML Code:

var ajax_processor = './ajax_processor.php'

onload = function(){stats_capture('', null)}

function loadXMLDoc(url) 
{
 if (window.XMLHttpRequest) 
 {
  req = new XMLHttpRequest()
  req.onreadystatechange = processReqChange
  req.open("GET", url, true)
  req.send(null)
 }
 else if (window.ActiveXObject)
 {
  req = new ActiveXObject("Microsoft.XMLHTTP")
   if (req)
   {
    req.onreadystatechange = processReqChange
    req.open("GET", url, true)
    req.send()
  }
 }
}

function processReqChange() 
{
 if (req.readyState == 4) 
 {
  if (req.status == 200) 
  {
   response  = req.responseXML.documentElement
   method = response.getElementsByTagName('method')[0].firstChild.data
   result = response.getElementsByTagName('result')[0].firstChild.data
   eval(method + '(\'\', result)')
  }
 }
}

function stats_capture(input, response)
{
 // The input variable is not used here but is present 
 // for conformity so other ajax functions using the
 // same functions that may have input.
 if (response !== null)
 { 
  // Response mode
  alert(response)
  return false
 }
 else
 {
  // Input mode
  alert('Sending stats, the following values are about to be sent to the server: screen width ' + screen.width + ', screen height ' + screen.height)
  url  = ajax_processor + '?stats_capture=' + screen.width + ',' + screen.height
  loadXMLDoc(url)
 }
}

ajax_processor.php

PHP Code:


<?php



if(!empty($_GET['stats_capture']))

{

    # record stats to DB here

    list($width,$height) = explode(',', $_GET['stats_capture']);

    

    # start: build and send the XML response

    header('Content-Type: text/xml');

    echo '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>'."\n".

         "<response>\n".

         " <method>stats_capture</method>\n".

         " <result>Stats confirmation, the server recorded the following values to the database: screen width {$width}, screen height {$height}</result>\n".

         "</response>\n";

    # end: build and send the XML response

}



?>

**Ronnie268** · 06-07-2009 02:04 PM

Thanks very much for that.

As I'm a js newbie, could you please explain the stats_capture.js line by line, so I know where to add new logging stuff?

Also, has anyone any ideas how to make a PHP fall-back for if JS is disabled? This would enable bot logging.

Thanks,

Ronnie268

**bokeh** · 06-07-2009 03:42 PM

Originally Posted by Ronnie268

could you please explain the stats_capture.js line by line, so I know where to add new logging stuff?

Any extra items just add to the stats_capture function. Also don't forget half the stuff you may want to log is available through the http headers so your logging script could capture them from the ajax request.

Originally Posted by Ronnie268

Also, has anyone any ideas how to make a PHP fall-back for if JS is disabled? This would enable bot logging.

Depends what you want to log. For example bots don't have screen width and height as they don't have screens.

**Ronnie268** · 06-08-2009 02:23 PM

Right. Thanks for that, but in what form should I put the stats to log. Could you show me an example or two, please.

Also, might someone tell me what each line of stats_capture.js does, because it helps to understand it for debugging/expansion.

Thanks,

Ronnie268

**bokeh** · 06-09-2009 02:35 AM

First two functions do the request and response.

The third function (input phase) collects the data and sends it to the first function for transmission to the server. When there is a response from the server (response phase) that response is return to the third function (by the second function). In the PHP response script (line 12) php is telling the javascrit which function to return the response to as there may be more than one javascript function that possesses the responses.

In this example I've just used one variable which contains both the screen width and height delimited by a comma. If you choose you could send a whole string of variables and process them as you wish in PHP.

**Ronnie268** · 06-09-2009 10:16 AM

Thanks for that.

What does processReqchange do? Is it needed if you don't want to send a response?

I've thought of a PHP fallback. Use the base PHP logging script to record basic stats and to write the javascript. Then if the javascript fails, the basic logging is still done.

Thanks,

Ronnie268

**Mindzai** · 06-09-2009 12:33 PM

You could also parse Apache logs depending on what sort of stats you are after.

**Ronnie268** · 06-09-2009 12:39 PM

Thanks for all your help in this. It works! I shall definitely be adding a link to your website in the credits when I release the program!

All the best,

Ronnie268

**bokeh** · 06-09-2009 04:11 PM

Originally Posted by Ronnie268

What does processReqchange do? Is it needed if you don't want to send a response?

Ronnie, it's like this, you just want your code to do this one job, but when I wrote that code I tried to make it as reusable as possible so that when someone else comes along who wants to have background communication with the server for another reason they will already be able find 75% of the code they need.

**Ronnie268** · 06-10-2009 09:35 AM

Would this work across websites, like say if I my domain were example.com and I had a user who wanted to use it on foo.com, could I tell him to put

Code:

<script type="text/javascript" src="http://example.com/analytics.js"></script>

in his HTML document?

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