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PHP doesn't process the form

I'm having a little problem here.
I have a form with a jQuery that disables the submit input when the form is submited.The problem is: I use PHP to process the data when the input submit is clicked. But apparently the button is being disabled first, then PHP can not perform the processing. I need to find a way to prevent this, take a look in the code snippets:
<form class='send' action='{$_SERVER['PHP_SELF']}' method='post'>
<!--Form data-->
<input type='submit' name='finish' value='Send'/>
</form>
jQuery function to disable:
$('.send').on('submit', function()
{
$(this).find('input[type="submit"]').prop("disabled", true);
});
And then the PHP code to process:
if(isset($_POST['finish']))
{
//Do things
}
As I said, the PHP don't process the form because JS disabled the button to prevent multiple submitions. How to process PHP before disable the button? Thanks!

Since you are disabling the submit button it will not get send over to to server in the $_POST variable so your code doesn't work, as you have said.
Another way to do what you are looking for is to create a hidden HTML input
<input type="hidden" name="form">
Then when you check if the form is send, you will use
if(isset($_POST['form']))
{
//Do things
}

You can solve it easily changing your submit button by a simple button:
<form class='send' action='{$_SERVER['PHP_SELF']}' method='post'>
<!--Form data-->
<input type='button' name='finish' value='Send'/>
</form>
$('input[name="finish"]', '.send').on('click', function(){
$(this).prop('disabled', true);
$('.send').submit();
});

Making form's onsubmit to work only for particular submits

In PHP program, I have JS function which validates submit <form ...onsubmit='return isOK();'>. It works OK. The problem is I want it to work only for particular submits, not for all. Is there any way inside the JS function to find out which submit was pressed, or some PHP trick

instead of onsubmit u can use onClick.
<input type="submit" onclick="return pressSubmit1()" value="submit1" />
<input type="submit" onclick="return pressSubmit2()" value="submit2" />

<form action="action.php" method="post">
...
<input name="submit" type="button" value="check me" onclick="submitform('check')" />
<input name="submit" type="button" value="do not check me" onclick="submitform('not check')"/>
</form>
in javascript:
function submitform(check)
{
if(check=='check') checkfrom();
}
in PHP
if($_POST['submit']=="check me")
checkform();

<form class="allowed" onsubmit='return isOK();'>
----
function isOK() {
if($(this).hasClass('allowed')) {
// Do stuff
}
}

your question is not clear, are you using a single submit button or different ones. If you're using different submit buttons then ofcourse you can make checks based on the id of the submit button. On the other hand if is a single submit button then it depends on what the conditions are for submitting or not submitting

It's better you write some HTML and Java Script code which you are using. So, it's easy to correct mistake is you have made somewhere in code snippet.

We can check which submit button is clicked, using PHP.
In the PHP page corresponding to the form submit, write
if(extract($_POST) && isset($submitbtn1)) {
// some validation for first submit button
}
elseif(extract($_POST) && isset($submitbtn2)) {
// some validation for second submit button
}
Note: we can use $ followed by submit button name inside the extract function. ie. $submitbtn1 is same as $_POST['submitbtn1']

Yes different onclick looks fine as mentioned in the accepted answer. But in the event handler you should have the
code as below. Note the preventDefault.
Also since submit is A button that submits the form. You can use button type instead of submit type and then there is no need for preventDefault. Here is the link of the code http://jsbin.com/wikose/4/
function testlogin(){
event.preventDefault();
var test = 'not validated';
if(test === "validated")
alert("not valid login");
else
$('form').submit();
return false;
}

jquery submit form with button on event change

when a checkbox is checked, i want the form to submit. However I need parameters contained in my submit button to be part of the request.
This bit of script submits the form but not using the button. I guess because jquery submits it some other way.
$(e.target).find("input[type='radio']").attr("checked", true)
$(".edit_booking").submit()
I've tried pointing jquery to the button containing the params via it's ID and using a click event, but this doesn't work either.
$(e.target).find("input[type='radio']").attr("checked", true)
$("#bookings_next").click()
Bits of the form:
<form novalidate="novalidate" class="simple_form edit_booking" id="edit_booking_9486" action="/venues/plymouth/bookings/9486" accept-charset="UTF-8" method="post">
.............
<input type="submit" name="forward_button" value="Next step" id="bookings_next" />
Many thanks

aha, simple!
$('#bookings_next').trigger('click');
I have to trigger the event.

jQuery / Bootstrap3: Disable/hide button after submit

I'm new to javascript, but I've searched extensively about this and tried dozens of different alternatives. Most of them did nothing at all, others prevented the form from submitting!
I have the following form:
<form name="buy" action="process_order.php" method="post">
<input type="hidden" name="itemid" value="{$itemid}">
<button type="submit" id="submit" name="submit" class="btn btn-sm btn-success">Buy</button>
</form>
I want to prevent double submissions by either disabling the submit button after submit or just make it disappear, whichever works best.
I have tried multiple JS approaches and I dont even know which one is best, so I wont provide one here to avoid confusion.
I'd be thankful if you could provide me a full javascript <script> snippet and anything else I eventually need. I would prefer to not use Ajax here, but let me know if that would help.
Many thanks!

You can use jQuery for this.
$('form[name="buy"]').on('submit', function() {
$('#submit').prop('disabled', true);
});
That will disable the submit button as soon as the form is submitted.
As #rolodex has pointed out submitting the form will refresh the page, thus the disabled button becomes enabled again. This is what I would do if not using Ajax (as #rolodex's answer does):
<form name="buy" action="process_order.php" method="post">
<input type="hidden" name="itemid" value="{$itemid}">
<button type="submit" id="submit" name="submit" class="btn btn-sm btn-success"<?php if(isset($_POST['itemid'])) echo ' disabled'; ?>>Buy</button>
</form>
Thus once someone has submitted the form, the button becomes disabled. This doesn't stop someone refreshing the page again without form data though, but neither does using Ajax. The only way to get around that would be to use cookies.

In order to prevent second submission after the first, you have to use AJAX, as far as I am concerned, because every time the form is submitted, the page will refresh and there will not be any indication if the form is already submitted or not. My approach here will use jQuery and here's how you do it.
First, remove the attribute action and method from your <form> which we will replace with the AJAX call. Just as simple as this;
<form name="buy">...</form>
Secondly, include the necessary jQuery library;
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
Then the script;
<script>
$(function(){
$('form').on('submit', function(){
var data = $(this).serializeArray()
$.post('process_order.php', data, function(r,s){
console.log(r)
});
// Updated answer (change submit button's ID to class instead);
$(this).find('.submit').prop('disabled', true);
return false;
})
})
</script>
And that's all. It's identical to #Styphon's answer, but I believe that this is more complete and I hope this helps.
Cheers!

I use this (jQuery required):
<script>
var submiting = false;
$(function() {
$('form').submit(function() {
if (!submiting) {
submiting = true;
$('button[type=submit]').prop('disabled', true); //cosmetic
} else {
return false;
}
});
});
</script>
With this code, when the form is submitted, the boolean will prevent any further submission (ie. the user clicks really fast on the submit button) and will disable the button preventing further clicks.
But a much better aproach is described here:
Prevent double submission of forms in jQuery

Here is a neat solution
$('form').submit(function(){ //prevent multiple submit
$(':submit', this).click(function() {
console.log("submit prevented"); // Debug purpose.
return false;
});
});
If you submit form for instance 4 times, you will see the 3 "submit prevented" output.
$("#btn").trigger("click");
$("#btn").trigger("click");
$("#btn").trigger("click");
$("#btn").trigger("click");

Form fields value get reset without page load

Following is my code in which i am trying to accomplish, when user clicks on the submit button then my javascript function sets all the value to null in the textfields of the form whose id='contact_form' without loading the page . Kindly let me know how can i modify the following code to accomplish the functionality i've been trying to do.
Thanks!!
<script type='text/javascript'>
$(document).ready(function(){
$('#love').click(function(e) {
document.contact_form.name.value = '';
alert('aloha!!');
//stop the form from being submitted (not working fine)
e.preventDefault();
}
}
</script>
<form name='abc' action='' id='abc' >
<input type="submit" id='love' />
</form>
I have also tried the following function it worked fine but its not preventing from the page load
<script type='text/javascript'>
function js(){
document.contact_form.name.value = '';
//stop the form from being submitted (NOT WORKING!!)
preventDefault();
}
}
</script>

If you try onsubmit="return false;" in the form tag your form will not be submitted. Unfortunately it will NEVER be submit. Unless you are not planning to submit it via AJAX you have to modify your onsubmit event like this:
<form onsubmit="return callFunction()">
function callFunction() {
if(condition)
return true;
else
return false;
}

$("#abc").submit( function() {
// do everything you want.
return false; //will prevent the reload.
});

To have a function execute when the form submits you have to do something like this;
<form onsubmit="return validate();">
your form here
</form>
Then you can have your check in a function called 'validate()' (or whatever you want to call it)
Make sure the validate() function returns true is the form is allowed to submit, or returns false if the page is not allowed to submit.
Also put id's and names on your input elements, that way you can access them much easier.

Assuming you have an HTML like this :
<form>
<input type="text" id="text" />
<input type="submit" id='submit' value="clear above field without reloading" />
</form>
And you want the text field value to clear when a user submits without reloading using jQuery, then following script will be your remedy :
$(function(){
$('#submit').click(function(){
$('#text').value('');
})
});

A form can be submitted in many ways, not only by clicking on a submit buttons. You should really watch for submit events, and cancel them with preventDefault (instead of click events that might trigger the submit). See #user1359163's answer.
But you problem seem to be document.contact_form.name.value. There is no property contact_form on the document object, so this will raise an error. The preventDefault is not executed, your form gets submitted and you never see the error. Set your debugger to "Stop on errors"!
You might want something like document.forms["contact"], but I don't know your HTML. An id selector for the input element would be the better choice.