Ajax Tutorial : Ajax Help and Tutorials

Archive for Ajax Basics

Simple Ajax using Prototype. Part 2

November 30, 2006 at 10:24 pm · Filed under Ajax with PHP, Ajax Basics

Ajax Updater - Update a DOM element ID from a Server Script

This example is probably the simplest example you will ever find.
We are going to use the prototype feature ‘ajax.Updater’ (see part one for more details on prototype).

ajax.Updater allows you to specify an element ID and script URL - and whatever the script URL prints will appear in your element ID. Simple as that.

The example below simply returns the Server time each time the button is clicked.

I’m not going to explain this bit by bit as it is just so easy to grasp.

Remember, you will need the prototype library in order to use this!

Here is the HTML/JavaScript code:

<html>
<head>
<script src="dist/prototype.js" type="text/javascript"></script>
<script type="text/javascript">
function ajaxUpdater(id,url) {
 new Ajax.Updater(id,url,{asynchronous:true});
}
</script>

</head>
<body>
<div id="updateme"></div>

<input type="button" value="Update" onClick="ajaxUpdater('updateme','updateme.php')">
</body>
</html>

And now the PHP code:

updateme.php

  echo “Server time is: “.date(”Y-m-d H:i:s”);

The above example has no real use, but in the real world there are many things which can be done. For example I recently wrote an automatic session log-out script, which automatically kills the session after a given period and send the user back to the login page (very handy for secure sites). I’ll post that script up soon.

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Simple Ajax using Prototype. Part 1

November 29, 2006 at 9:44 pm · Filed under Ajax with PHP, Ajax Basics

This is part of one of many such tutorials covering Ajax with Prototype.

If you do not want to get your hand to dirty with custom Ajax code, then using the extremely handy toolkit from prototype may be perfect.
Prototype is a very well written JavaScript framework/toolkit and come with an Ajax class to make things nice and easy.

In this simple example I’ll show you just how easy Ajax calls are. But you will need to have your own copy of prototype (its free!).

On a side note… if you like fancy JavaScript effects, you can extend prototype with another library called script.aculo.us - I promise, with these you will have endless hours of fun!!

On with the example
I’ve attempted to simplify things as much as possible. In this tutorial we will type some text into a standard form field, hit a button and see the results appear below. In the background, our button click will trigger our JavaScript function, and pass the text through Ajax to a server-side PHP script. This PHP script will write our text back to an other JavaScript function on our page and print the text out on the screen.

First we include our prototype library:

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

Then we create two of our own functions, the first one is the main script which passes our text to the Server (PHP script in this case). The second function handles the response from the PHP script and prints the results to the browser.

<script type="text/javascript">
/* ajax.Request */
function ajaxRequest(url,data) {
  var aj = new Ajax.Request(
  url, {
   method:’get’,
   parameters: data,
   onComplete: getResponse
   }
  );
}
/* ajax.Response */
function getResponse(oReq) {
  $(’result’).innerHTML = oReq.responseText;
}
</script>

In the getResponse function above, noticed the function call $(’result’) - this is a feature of prototype which basically replaces ‘document.getElementByID(’result’)’.

Yes, that is all we need in terms of JavaScript. I told you it was simple!!

Next we have the form:

<input type="text" id="myval" size="10">

<input type="button" value="GO" onClick="ajaxRequest('parse.php', 'val='+$F('myval'))">

<div id="result"></div>

Nothing fancy with the above. In order to call our JavaScript functions, we are using the ‘onClick’ event of the button.
We are passing in two values here; first the server-side script file ‘parse.php’ and the value we want to send.
We must pass in the paramater name and value (for example: ‘val=myvalue’, just like any querystring!), the parameter name in the case is ‘val’ and the value is the text in our text field. We refer to this value using another prototype function $F() which is really just ‘document.getElementById(’myval’).value’.

On the server-side, our PHP script takes the value we passed $_GET[’val’] and prints it back to us as ‘You entered: yourvalue’ (where ‘yourvalue’ is what your entered in the text field!).

parse.php

if(isset($_GET[’val’])) {
  echo “You entered: “.$_GET[’val’];
}

This is a very simple example of using just one of prototypes Ajax features, there are many more to explorer which I will cover soon.

Have fun!

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AJAX generic form parser

July 7, 2006 at 9:31 pm · Filed under Ajax with PHP, Ajax Basics, JavaScript

AJAX Generic Form Parser - With Validation:

In this tutorial I’ll show you a simple method to pass any HTML form through AJAX without the need to hard code all form fields into the JavaScript or Server Side Script. Using this simple piece of JavaScript you can reuse it as is with any form, saving a lot of time. I’ve even added basic validation to certain form element types (which would be expected).

Okay, straight to the main JS code.

var req = createXMLHttpRequest();

function createXMLHttpRequest() {
 var ua;
 if(window.XMLHttpRequest) {
 try {
  ua = new XMLHttpRequest();
 } catch(e) {
  ua = false;
 }
 } else if(window.ActiveXObject) {
  try {
	ua = new ActiveXObject(”Microsoft.XMLHTTP”);
  } catch(e) {
	ua = false;
  }
 }
return ua;
}

function sendRequest(frm, file) {
 var rnd982g = Math.random();
 var str = “”;
 if(str = getForm(frm)) {
  req.open(’GET’, file+’?'+str+’&rnd982g=’+rnd982g);
  req.onreadystatechange = handleResponse;
  req.send(null);
 }
 return false;
}

function handleResponse() {
 if(req.readyState == 4){
  var response = req.responseText;
  document.getElementById(”results”).innerHTML = response;
 }
}

function getForm(fobj) {
 var str = “”;
 var ft = “”;
 var fv = “”;
 var fn = “”;
 var els = “”;
 for(var i = 0;i < fobj.elements.length;i++) {
  els = fobj.elements[i];
  ft = els.title;
  fv = els.value;
  fn = els.name;
 switch(els.type) {
  case "text":
  case "hidden":
  case "password":
  case "textarea":
  // is it a required field?
  if(encodeURI(ft) == "required" && encodeURI(fv).length < 1) {
	alert('''+fn+'' is a required field, please complete.');
	els.focus();
	return false;
  }
  str += fn + "=" + encodeURI(fv) + "&";
  break; 

  case "checkbox":
  case "radio":
   if(els.checked) str += fn + "=" + encodeURI(fv) + "&";
  break;	

  case "select-one":
	str += fn + "=" +
	els.options[els.selectedIndex].value + "&";
  break;
  } // switch
 } // for
 str = str.substr(0,(str.length - 1));
 return str;
}

The JavaScript code above is split into 4 functions, here is an overview of what each function does.

createXMLHttpRequest() - This is the function which will establish the AJAX connection object, this is called as soon as the JS file is loaded.

sendRequest() - This function is the one which is called when the form is submitted. This function requires (passed in) the ‘Form Object’ and the ‘File Name’ of the script which will receive the form data. When this function has been called, it takes the form object and passes it to the JS function getForm() which in turn parses the whole form extracting all the data. sendRequest() then takes the open AJAX connection and passes all the data to the PHP file form processing. Finally when the request from the PHP server script is returned, it writes out the reply to an element on the screen with the div ID ‘results’.

getForm() - This is the magic, this function reads through the whole form and extracts the field data before returning it back to sendRequest(). It handles radio, text, password, textarea, select and checkbox field types. It even looks for validation requests on text, password and textarea fields (which is enabled by using title=”required” in the form element).

Simple :)

Next is a very simple form with a mixture of field types and validation requests (nothing fancy here). Also included at the bottom is the div which prints out the results to the browser.

<form>
Option One:
 <input name="radiobutton" type="radio" value="opt1">
Option Two:
 <input name="radiobutton" type="radio" value="opt2">
Option Three:
 <input name="radiobutton" type="radio" value="opt3">
Text One*:
 <input type="text" name="textOne" title="required">
Text Two:
 <input type="text" name="textTwo">

<select name="mySelect">
 <option value="selectedOne">Select One</option>
 <option value="selectedOne">Select One</option>
 </select>


<input type="button" value=" go " onClick="sendRequest(this.form, 'process.php')">
</form>
<div id="results" />

As you can see the form trigger which calls the AJAX actions is set in the button using the onClick method. Also note I’ve added title=”required” to the ‘textOne’ field - this means the user will not be able to submit the form unless this field contains a value.

Finally here is a very stripped down Server script in PHP which takes the form values and returns them formatted back to the JS (you could do anything with the data at this stage!).

process.php

if(isset($_GET[’rnd982g’])) {
 foreach($_GET as $a => $b) {
 if($a == “rnd982g”) {
  // ignore this random number
  // only used to prevent browser caching
 } else {
  echo “<b>$a</b>: “.stripslashes(htmlentities($b)).” “;
 } // if
 } //foreach
die;
}

You could easily change the above to generate an email or add the form data to a database, the above example will echo out the results which are passed back to the div tag below the form.

There you have it, short and sweet (I hope) - I’ve intentionally kept the example scripts to a minumum but with still enough to be useful. Please feel free to take this and mess around with it.

Have Fun!!

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Ajax Tutorial : Ajax Help and Tutorials

Archive for Ajax Basics

Simple Ajax using Prototype. Part 2

Simple Ajax using Prototype. Part 1

AJAX generic form parser

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