Develop Reference

How to prevent repeatative submit while using ajax or javascript?

I have a controller in c# and inside the controller there is a save method. The save method saves/updates data that is submitted by submit button click and javascript. The problem is, if you click on the button multiple time, it should only process the very first click and rest of them should be identified as duplicate submit and should be discarded by controller. How to do this in c# mvc web application?

Disable the button after it's clicked. So it can just be clicked once.

Simple way
when button clicked disabled it then actived again after you got response result from ajax! u can also add loader that make ur web look so cool!
<button id="btnSend" onClick="send()">submit</button>
<script>
btnSend=document.getElementById("btnSend");
function send(){
btnSend.disabled=true;
//set disabled button here
$.ajax({ type: "GET",
url: "http://www.google.de",
async: false,
success : function(text)
{
btnSend.disabled=false;
//set active to button
// add your code here
},
fail : function(text)
{
btnSend.disabled=false;
//set active to button
// add your code here
}
});
}
</script>

I would also disable the button on the client side. But you could also check if the submitted data is different from the stored data. If no changes were made you could just return without further saving logic.
Should it be possible to just save the data once? Maybe a redirect to a different view after saving could be a possible solution in special cases.

How would I save input from a text box and then move to the next page? (Javascript/HTML)

As part of my new job, I'm creating a small form where users answer a question and this is then saved and output at the end of the pages.
I started off with having a prompt where users were asked to explain their answers (which worked perfectly!), however I've been asked to change this to an input box.
Essentially the process I need to do is:
User enters in text box -> Clicks next button -> save input to session variable and move to next page
So far, I have the following HTML in the body:
<form name="next" action='#' method=post>
Explanation:<input type="text" id="xp" required><br>
<button class="nextButton" onclick="return explanation()">Next</button>
</form>
with the corresponding javascript:
function explanation() {
var exp = document.getElementById('xp').value;
sessionStorage.setItem("p1_reason", exp);
alert(exp);
document.location.href = 'page2.html';
}
So far the result of this is:
The text box is cleared, but nothing is saved or displayed onscreen
The next page is not displayed.
Any help/advice would be appreciated. I'm relatively new to js so I'd be grateful! I'm well aware that there are similar questions around, I just can't seem to see where I'm going wrong.

#David is right. You can add event.preventDefault() function to prevent the form from its default behaviour, which is submitting. Otherwise your code seems to work.
function explanation() {
event.preventDefault(); // <-- add here
var exp = document.getElementById('xp').value;
sessionStorage.setItem("p1_reason", exp);
alert(exp);
window.location.href = 'page2.html';
}
Also, don't use document.location.href, it's deprecated. It's better to use window.location.href instead.

When you click on nextButton, the browser run explanation() and then try to execute the action of your form. Because your action is action='#' it just try to reload the page, preventing document.location.href for working properly.
Actually, you can try to don't enter nothing on the box and click on the button. The redirect will work because the form is empty, so there is nothing to submit.

When I disable submit button (after form submit) the page does not load

I have an HTML form which submits to another page via POST. Nothing special about it, except that after the form validates I try to hide and/or disable the submit button so that it cannot be double-submit, while also telling the user the next page might take a while to load.
The relevant code is:
jQuery(document).ready(function () {
jQuery("form#form").submit(function() {
var result = validate();
jQuery(this).find('input[type=submit]').prop('disabled', true);
jQuery("#submit-button-wrapper").html(jQuery("#submit-button-wrapper").html()+
"<br/><br/><span style='margin: 25px; padding: 5px; background: yellow; "+
"width: 100%; font-weight: bold;'>Loading... this may take a few minutes! "+
"<i class='fa fa-spinner fa-spin' style='color: blue;'></i></span>");
return result;
});
});
function validate() {
return true; // Does stuff, then returns a simple true or false
}
By request, here is the (very simple) button wrapper HTML:
<div class="col-sm-12" id="submit-button-wrapper">
<input type="submit" value="One More Step" />
</div>
When the I remove the which changes the button wrapper's HTML, the form submits just as you'd expect. When I have that line in, however, it still calls the next page and executes that code, without the displayed page ever changing.
I have tested in both Chrome and Firefox, so I know it's not a browser issue, but this is really weird behavior. What am I doing wrong?
My goal: (1) validate the user's input, (2) give the user a clue that the page is going to take a while to load and (3) display the output from the action="complete.php" page once the PHP on it has run.

Maybe you can achieve this with $ajax and show results on the same page.
Send POST data to /some.php
After sending data, give feedback to user changing button behavior
When the task is complete, receive data and verify success or error and act accordingly. If OK, change button text to "complete!" or something else, and append response data to some div. If NOT OK, give feedback as well.
In code:
$("form#form").submit(function(e) {
e.preventDefault();
$.ajax({
method: "POST",
url: "some.php",
data: $(this).serialize(),
dataType : 'json',
timeout: 2000,
cache: false,
afterSend: function() {
/*change button behavior here*/
},
success: function(result) {
if (result === "ok"){
/*maybe append data to div and update button text to complete*/
} else {
/*if result not ok, send feedback*/
}
}
});
});
BTW: ajax documentation http://api.jquery.com/jquery.ajax/

When you return true (if validated) then the form is submitted. However, you're changing the DOM / submit button wrapper and essentially removing the submit button, right? Likely that is what is causing your problem. Leave the submit button wrapper alone. If you want to display a message display it as an overlay or hide the submit button wrapper and show the message wrapper in its place, don't remove the submit button altogether.

I know that you're just showing a slight jQuery and HTML portion of the script, but that isn't quite enough to figure out your problem. Since not all of it seems to be there because you mention action="complete.php" but I don't see that within your jQuery or HTML sample of code. So I have a few questions of my own.
Is the form small or large. If it's a small form then why aren't you displaying the output on the submit page? You could do that with what you currently have but a single PHP or ASP page could save you on amount of pages to make and what not. As a side note, depending on size of the form, you can do the validation on same page or continue to use action="" for it if large.
Do you have need for a database file or are you saving to one? If you do/are, you could write to the DB file, have the submit open the next page and view what was saved in the database on that new page. Again, you can probably use a single PHP or ASP page.
This last part sounds more valid for your purpose. You could use location.href="http://www.domain.com/home.html";
or use window.location("http://www.domain.com/home.html"); to redirect to the new page.
On another matter about some of the comments others made.
You don't exactly need the + unless you're dividing each of those out into their own separate lines when you could just use one line to do that. That's probably what confused Rajesh about the '. In fact I'm not sure why you yourself mentioned the + when referring to Rajesh comment about "concat string" and "append" ,because those two have nothing to do with the +. In fact to take a guess, he might have been referring to your jQuery("#submit-button-wrapper").html(jQuery("#submit-button-wrapper").html() which kinda looks like a concat string.
Speaking about append, not really needed unless for example you're doing something like giving the user the option to add rows to a form question.

How to use checkbox value asdata parameter in ajax

I need to reload a page when clicking in a submit button. What the new page should show depends on the checkboxes selected previously to the reloading.
My problem is that, when I click "submit", $("button").click(function()... takes the correct values but $(document).ready(function ()... takes always the values true (which are selected as default).
How can I save those values before the reloading so that I can use them on $(document).ready(function ()...? Can I send them as data parameter
$(document).ready(function() {
var selectedCheckboxes = new Array();
$.ajax({
url: 'getNewForm.php?accion=value1',
data: 'selectedCheckboxes',
dataType: 'json',
error: function() {
alert("ERROR");
},
success: function(res) {
//Do something
}
}
});
$("button").click(function() {
var selectedCheckboxes = new Array();
selectedCheckboxes[0] = document.getElementById("checkbox1").checked;
selectedCheckboxes[1] = document.getElementById("checkbox1").checked;
});
});
Note: I did var selectedCheckboxes twice trying to get different results, don´t know where I should do it.

You have several problems here:
You have a syntax error in your code sample. Make sure the code you post to StackOverflow compiles and runs without syntax errors (assuming you're not asking why a particular code snippet is generating syntax errors :) ).
The data attribute of your AJAX request is incorrectly specified as the literal string 'selectedCheckboxes', which means that your browser will send the literal string "selectedCheckboxes" as the payload to your server.
In addition, as you correctly surmise, you don't correctly handle the initialization of selectedCheckboxes. Variables initialized with var in JS are scoped to the containing function, which means the selectedCheckboxes declaration inside your click() handler are never going to be seen outside it.
Also, you're getting the value of "checkbox1" twice; you probably want to get something named "checkbox2" or similar. Related: If you are just serializing the only inputs in the form, use jquery's serialize() method so you have less code.
If you're really reloading the entire page anyway, don't use an AJAX request to do it? Using AJAX for form submissions is common when you do not want to reload the entire page (see below), but for your stated use case, it adds complexity you don't need. Just have a simple form with checkboxes and a submit button, and let the browser do it's default action.
Here's an example of using AJAX to submit a form behind the scenes, without reloading the entire page:
http://jsfiddle.net/Palpatim/rLeGv/
Given the HTML:
<form id="checkboxForm">
<input type="checkbox" name="check" value="check1" checked="checked" id="ch1"/>
<label for="ch1">check1</label>
<br/>
<input type="checkbox" name="check" value="check2" checked="checked" id="ch2" />
<label for="ch2">check2</label>
<br/>
<button>Click me</button>
</form>
This JS will submit a form when the button is clicked:
$(document).ready(function() {
$("button").click(function() {
$.ajax({
url: 'getNewForm.php?accion=value1',
data: $('#checkboxForm').serialize(),
dataType: 'json',
error: function() {
alert("ERROR");
},
success: function(res) {
alert("SUCCESS");
}
});
});
});
As far as loading a new page with the previous selections, you will have to maintain the state somehow. Your options include passing the state back from the server, storing the selections in the browser's local storage, or a cookie. I'd suggest passing the state back from the server, but your use case is a bit unclear.

database query via javascript & servlet

I am trying to do a simple query for info from a database through an html page. I've got all the backend stuff working fine, but I'm having trouble on the client side. I currently have a form where the user submits their ID# to get some info on their case.
But with my current setup, it returns an entirely new page and I just want to read in a text string, process it and update the content on the current html page without opening up a new one and replacing the old one. How can this be done?
Here's my code so far:
function showInfo() { } // I want to make the request here instead
<form name="register" action="http://localhost:8080/testapp/authenticate" method="get">
<p><label for="badge">ID #:</label>
<input id="badge" name="ID" type="text" pattern="[0-9]{6}"
placeholder="xxxxxx">
<button id="checkButton" type="submit" onClick="showInfo()">Enter</button>
</p>
</form>

My guess is that you're actually submitting the form, which is posting back to the server. What you will want to do is cancel the form from submitting and submit it using AJAX (which is what I believe you want?).
To do so, your showInfo() function should do one of these three things (I can never remember which one)
return false;
cancel the event, something like e.preventDefault()
stop the propagation, something like e.stopPropagation()
Once you've successfully prevented the form from hard-submitting, you can then do what you'd like by submitting your data via AJAX and manipulating your response however you'd like.

1st - Jason is absolutely right that what you want for this situation is AJAX, below is an example in motion.
2nd - You should be using a Javascript library such as jQuery, which might look intimidating (as it did for me at first), but it is really easy and completely worth the small effort to get it going.
3rd - With jQuery, your application tidbits should look something like this, using the example you provided:
HTML -
<p>
<label for="badge">ID #:</label>
<input id="badge" name="ID" type="text" pattern="[0-9]{6}"
placeholder="xxxxxx">
// Please note that I removed the onClick section from the line below.
<button id="checkButton" type="button">Enter</button>
</p>
JQUERY -
// The default function you described to take information and display it.
function showInfo(data) {
// Insert your function here, probably using JSON as the Content Type
}
// This is the key AJAX function, using jQuery, that takes your info and gets a
// response from the server side, the sends it to the function above in order for it
// to be displayed on the page.
function processIdInfoCheck() {
$.ajax({
type: 'post',
url: '/http://localhost:8080/testapp/authenticate',
data: {
'id': $('#badge').val();
},
dataType: 'json',
success: displayIdInfoReturn,
error: function () {
alert("There was an error processing your request, please try again");
}
});
}
// When the page loads, the code below will trigger, and bind your button click
// with the action you want, namely triggering the AJAX function above
(function ($) {
$('#checkButton').bind('click', processIdInfoCheck);
})(jQuery);
Just remember, AJAX takes some effort to get the desired effect, but when you look at page load times, request numbers, etc... It is totally worth it. Please let me know if this was helpful and if you need any specifics.