ajax form validation

[ksmatthews]

HI All,

 

I would like to ask a question about ajax and form validation

 

I am using some ajax code as follows ...

 

function showHint(str)

{

xmlHttp = GetXmlHttpObject();

 

if (xmlHttp == null)

  {

  alert ("Browser does not support Ajax HTTP Requests");

  return;

  }

 

// get ID of destination object

results = validation_fields.split("|");

destination_id = results[2];

 

if(str.length==0)

  {

    document.getElementById(destination_id).innerHTML="";

    return;

  }

 

// assemble URL string

var url = "../global_php/ajax_validation.php";

url = url + "?value=" + str.value + validation_fields;

url = url + "&sid=" + Math.random();

 

// The onreadystatechange property stores the function that will process the response from the server

// Each time the readyState changes, the onreadystatechange function will be executed.

xmlHttp.onreadystatechange = stateChanged;

xmlHttp.open("GET", url, true);

xmlHttp.send(null);

}

 

 

// FUNCTION: Checks server state and returns data to calling form

// PARAMETERS: NONE

// RETURNS: void (populates form object with returned data)

function stateChanged()

{

// The readyState property holds the status of the server's response

if (xmlHttp.readyState == 4 || xmlHttp.readyState == "complete")

  {

    // capture result

var response = xmlHttp.responseText;

 

    // The data sent back from the server is assigned to submitted destination

    document.getElementById(destination_id).innerHTML = response;

  }

}

 

OK. The xmlHttp.responseText will show on the form whatever my php script echoes - in this case error

messages for incorrect input.

 

I need to be able to process those ajax generated messages client side in order to prevent  my form from

being submitted. At the moment the messages are displaying OK but the user can choose to ignore them

and submit erroneous data anyway.

 

How can ajax and javascriipt be used to actually enforce client side validation ?

I have thought about disabling the submit button but how ??

 

regards,

 

Steven M

 

[stylusrose]

first of I do believe you're on the wrong board, second off:

 

http://www.yourhtmlsource.com/javascript/formvalidation.html

 

answer

[BlueSkyIS]

you're best off using validation in PHP on the server, in addition to or instead of client-side validation. anyone can turn off Javascript and bypass Javascript validation (and nuke ajax as well). If you don't also validate on the server, you leave yourself open to invalid submissions.

 

imo, ajax is good for data-intensive operations where there are many values to choose from and sending them all to the browser at once wouldn't work well. for instance, ajax is a good choice to provide a list of possible zip codes for a selected state. you don't want to list every single US zip code for the user to pick from, so you could use ajax to reduce the selection based on the user's state selection.

 

but, if you also want to validate client-side, add an onsubmit() handler to the form, returning true (will submit) or false (won't submit) from a javascript validation function.

 

http://www.w3schools.com/jsref/jsref_onsubmit.asp

 

[RichardRotterdam]

plz dont crosspost

 

http://www.phpfreaks.com/forums/index.php/topic,197481.0.html