AJAX has changed the world of web development. Look at digg, facebook and gmail, thery are good examples to show the capability of AJAX. AJAX can create a highly responsive web interface and increase the user experience.
AJAX has changed the world of web development. Look at digg, facebook and gmail, thery are good examples to show the capability of AJAX. AJAX can create a highly responsive web interface and increase the user experience.
AJAX is abbrieviated from Asynchrounous javascript and XML. It's not a new technology, but the implementation of a group of technologies to achieve a seamless interaction between client and server.
Typically, xhtml and css to present the information, javascript is used to handle user interactions, and a server side language to perform the users' requests (and normally return data in XML format, in this tutorial, we won't do that), and it all is happening in the background using the Javascript XMLHttpRequest. Javascript plays a main role tie all these technologies together and create the asynchronous interaction between client ans server.
Advantages:
* Reduce connections and bandwidth to the server, images, scripts, stylesheets only need to be downloaded once * Reduce loading timew. User doesnt have to load pages again and again, it all happens in a same page! * Increase responsiveness and end user experiences.
Usability Guidelines:
* Always provide feedback to user. Let user know the server is processing the request. Indicate that using message or loading icon. * Prepare a plan to those users without Javascript support.
Introduction
So, you know about the goodness of AJAX. Let's learn a simple way to implement it.
In this tutorial, we will learn form submission using jQuery without navigate out from the page. It accepts user input, processes it and sends it to a php file called "process.php". The PHP script will send a notification email to the recipient. Of course, in case browser couldn't support javascript/XMLHttpRequest, we have a second plan ready, the form will submit the data using the normal form submission.
How do we do that? Easy, we specified POST and ACTION attributes in the FORM element, if browsers couldn't support it, that will submit the form straight away. If the browsers could support it, the javascript will cancel the submit button default behaviour. And we need to code the PHP script to support both GET and POST methods and produce the result accordingly. 1. HTML
In this sample, I'll keep everything as simple as possible. This is how it looks like view plaincopy to clipboardprint?
I'm using CSS to make the 2 columns layout - LABEL and Form Elements. Also, some important classes:
* .hightlight: Error indicator. if user had not entered anything in the textfield, it will highlight it and display an error icon * .loading: Loading animation icon. After user clicked on submit, if no errors were found, this icon will be displayed next to the submit button * .done: Success message. If the form is submitted successfully, display show this class
Finally, the Javascript code. I have added comments in each line to explain what it does.
First, we need a simple validation to ensure user has key in something. We can add more validations, like, email validation, valid character validation, length validation and so on. And it's a good practise to encode the data into URL friendly format as well.
What the code does:
* Get user's input * Validate the data, if error found, add the hightlight class, and stop the script * If no errors were found, all text field will be disabled and format the data to be passed to jQuery ajax method * jQuery will appened the data to process.php, so it will look something like this:
1. $(document).ready(function() { 2. 3. //if submit button is clicked 4. $('#submit').click(function () { 5. 6. //Get the data from all the fields 7. var name = $('input[name=name]'); 8. var email = $('input[name=email]'); 9. var website = $('input[name=website]'); 10. var comment = $('textarea[name=comment]'); 11. 12. //Simple validation to make sure user entered something 13. //If error found, add hightlight class to the text field 14. if (name.val()=='') { 15. name.addClass('hightlight'); 16. return false; 17. } else name.removeClass('hightlight'); 18. 19. if (email.val()=='') { 20. email.addClass('hightlight'); 21. return false; 22. } else email.removeClass('hightlight'); 23. 24. if (comment.val()=='') { 25. comment.addClass('hightlight'); 26. return false; 27. } else comment.removeClass('hightlight'); 28. 29. //organize the data properly 30. var data = 'name=' + name.val() + '&email=' + email.val() + '&website=' 31. + website.val() + '&comment=' + encodeURIComponent(comment.val()); 32. 33. //disabled all the text fields 34. $('.text').attr('disabled','true'); 35. 36. //show the loading sign 37. $('.loading').show(); 38. 39. //start the ajax 40. $.ajax({ 41. //this is the php file that processes the data and send mail 42. url: "process.php", 43. 44. //GET method is used 45. type: "GET", 46. 47. //pass the data 48. data: data, 49. 50. //Do not cache the page 51. cache: false, 52. 53. //success 54. success: function (html) { 55. //if process.php returned 1/true (send mail success) 56. if (html==1) { 57. //hide the form 58. $('.form').fadeOut('slow'); 59. 60. //show the success message 61. $('.done').fadeIn('slow'); 62. 63. //if process.php returned 0/false (send mail failed) 64. } else alert('Sorry, unexpected error. Please try again later.'); 65. } 66. }); 67. 68. //cancel the submit button default behaviours 69. return false; 70. }); 71. });
$(document).ready(function() {
//if submit button is clicked $('#submit').click(function () {
//Get the data from all the fields var name = $('input[name=name]'); var email = $('input[name=email]'); var website = $('input[name=website]'); var comment = $('textarea[name=comment]');
//Simple validation to make sure user entered something //If error found, add hightlight class to the text field if (name.val()=='') { name.addClass('hightlight'); return false; } else name.removeClass('hightlight');
if (email.val()=='') { email.addClass('hightlight'); return false; } else email.removeClass('hightlight');
if (comment.val()=='') { comment.addClass('hightlight'); return false; } else comment.removeClass('hightlight');
//organize the data properly var data = 'name=' + name.val() + '&email=' + email.val() + '&website=' + website.val() + '&comment=' + encodeURIComponent(comment.val());
//disabled all the text fields $('.text').attr('disabled','true');
//show the loading sign $('.loading').show();
//start the ajax $.ajax({ //this is the php file that processes the data and send mail url: "process.php",
//GET method is used type: "GET",
//pass the data data: data,
//Do not cache the page cache: false,
//success success: function (html) { //if process.php returned 1/true (send mail success) if (html==1) { //hide the form $('.form').fadeOut('slow');
//show the success message $('.done').fadeIn('slow');
//if process.php returned 0/false (send mail failed) } else alert('Sorry, unexpected error. Please try again later.'); } });
//cancel the submit button default behaviours return false; }); });
4. PHP
This PHP code can accomodate different type of submissions (POST and GET). If the user submitted the form using jQuery, process.php will get the data from GET. and if the browser couldn't run javascript, the data will be sent using POST. What it does:
* Retrieve user's input from either GET or POST method * If POST, set the $post variable to 1. This is to display the message instead of return the result * Then, perform the server side validation if the form was submitted using POST * If no errors were found, organize the data into a html email template and send it to the email we have specified. * Display the message if POST is used. Display result (either 1 or 0) if GET is used
not understand anything at least specify howmany files and which are they and what there filenames and extension and from where to where these files start and ends without this ask to leave a comment means simply wasting our time sorry for the comments