Develop Reference

How to collect a string from a radio input and send it to a useState? (React) [duplicate]

I have a MVC3 app using Project Awesome (http://awesome.codeplex.com/), but I am getting a weird behaviour on checkboxes. I have the following simple Html within a Modal popup <input type="checkbox" class="check-box" name="IsDeleted">
When I submit the form containing this element, its post value is 'on' instead of the expected 'true' (when element is checked).
Does anybody know why this is? I am assuming there may be some javascript somewhere messing with the form data, but wanted to check whether there isn't some HTML I am missing.
Thanks

Set the checkboxes value attribute to true and you will get true in your post value.

It's browser specific, I suppose, what to send when value is undefined. You need to defined value attribute on your radios/checkboxes to be sure what will be passed back to you. I would suggest value="1"

set data-val="true" and value="true" by deafult...
if checkbox is checked then returns true

Check Checkbox is checked or not if checked set Hidden field true else set hidden field false.
$('#hiddenFieldId').val($('#CheckBoxId').attr('checked')=='checked')

Surely you should just check if it is set - the value that it sends across is irrelevant, if it's not checked, then nothing at all gets sent when you POST.

Nothing worked!
I ended up on a hacky way after seeing the serialised form object just before posting to controller/action. Its not safe in case if anyone would have any textboxes inside that may contain ampersands. In my case, i had an array of checkboxes, so I did this hack after I am very sure, i won't have problems.
var formData = $("#form").serialize();
formData = formData.replaceAll('=on&','=true&');
if (formData.endsWith('=on'))
{
formData = formData.substring(0, formData.length - 3) + "=true";
}
Hope it helps to those 'someone' with my scenario. Happy hacking.

Use jQuery for cross-browser decision. And it will return true or false anyway.
$('#check-box-id').attr('checked' ) == true
if your checkbox has an id check-box-id. For your current version use the next (select by class name):
$('.check-box').attr('checked' ) == true

Use jQuery
var out=$('.check-box').is('checked')
If checkbox is checked out=true
else out=false

In HTML, add a input type="hidden" above checkbox:
<input name="active" id="activeVal" type="hidden">
<input id="active" type="checkbox">
Then, add a script as below:
$('#activeVal').val($('#active').is(':checked'));
$('#active').change(function() {
$('#activeVal').val($('#active').is(':checked'));
});
When you do eg. $('#your-form').serialize() in jQuery, you will get value of checkbox when checked active: true or uncheck active: false

Checkbox checked not passing an actual value?

My code checks the value of 2x checkboxes to equal true/false depending on a radio field. I see the checkboxes being ticket on the web page.
However, once they are passed over a HTML POST form, they have no values and always equal false.
If I give the checkboxes a value "TRUE" then of course they have only that value.
What am I missing here?
<script>
$(function() {
var MAIN= $("input[type='radio']");
var marketingPhone = $("input[type='checkbox'][name='marketingPhone']");
var marketingRobo = $("input[type='checkbox'][name='marketingRobo']");
MAIN.on('change', function()
{
if ($(this).val() == "TRUE") {
marketingPhone.prop('checked',true);
marketingRobo.prop('checked',true);
} else {
marketingPhone.prop('checked',false);
marketingRobo.prop('checked',false);
}
});
});
</script>
The fields are as follows:
<input type="checkbox" name="marketingPhone" value=""/>
<input type="checkbox" name="marketingRobo" value=""/>

Checkboxes, if not checked, do not get posted at all with the form.
So if you post a form with checkboxes even if they have some value but they are not checked, you can not get checkbox's values in $_POST or $_GET arrays.

You need to specify a value in the HTML. If a checkbox is checked, that value is posted. These values can be anything and are definitely not the same as the true/false that are used for the prop()-call (those just mean 'set or clear the check mark').
Example:
<input type="checkbox" name="marketingPhone" value="yes"/>
<input type="checkbox" name="marketingRobo" value="absolutely"/>
When both are checked, this is posted:
marketingPhone=yes&marketingRobo=absolutely
When not all are checked, the corresponding name=value are omitted from the posted data.
If you really want to post a value (e.g. "true" or "false") for every checkbox all the time, then the only way to do so is by adding hidden fields (one for each checkbox) that you control yourself, setting the value of the hidden field to "true" or "false" using script. You might as well then not set the checkbox value to prevent confusion on the receiving end.
Also be aware that form fields always post strings, so either treat them as literal strings or parse them into booleans on the receiving end.

How to disable enable a checkbox based on another checkbox?

Following code is generated by a for loop.
<form action="saveresponse.php" method="POST" name="mainForm">
<input class="cbox_yes" type="checkbox" name="yes[]" value="01.jpg"
onclick="spenable()" /> OK
<input class="cbox_sp" type="checkbox" name="sp[]" value="01.jpg" disabled />Special<br />
<input class="cbox_yes" type="checkbox" name="yes[]" value="02.jpg"
onclick="spenable()" /> OK
<input class="cbox_sp" type="checkbox" name="sp[]" value="02.jpg" disabled />Special<br />
etc etc upto n times...
Now, what I want is that on page load, all the sp[] checkboxes should be disabled and enabled only if their corrosponding yes[] checkbox is checked by user.
Javascript code I am using: (Just to check if JS is capturing the states of yes[] checkbox?
function spenable(){
var yes = document.mainForm.yes[].value;
if (yes == true)
//alert("true");
document.mainForm.yes[].value = checked;
else
//alert("false");
document.mainForm.yes[].value = checked;
};
};
But I am not getting any alert (Neither Yes, Nor No).
So, is yes[] (Square brackets) in second line is incorrect? Or my if/else condition is wrong in JS?
P.S. All the questions here at SO or on Google deal with only one case/pair.
P.S. If required, I can change yes[] to yes1, yes2, yes3 etc and corresponding sp1, sp2, sp3 where 1,2,3 is $i of For loop, but then how will I capture/refer to it in JS?
_UPDATE:_
The flow/conditions are(Clarification):
Initially Special checkbox will be disabled and OK checkbox will be unchecked.
Then if user checks Ok, Special gets enabled.
If user want, he can tick Special.
If, later, user changes mind and untick the OK, Special should be unticked as well as disabled again.

I used jQuery here for the sake of simplicity.
$("input[name='yes[]']").change(function() { //When checkbox changes
var checked = $(this).attr("checked");
$(this).next().attr("disabled", !checked); //The next checkbox will enable
});​ // or disable based on the
// checkbox before it
Demo: http://jsfiddle.net/DerekL/Zdf9d/
Pure JavaScript: http://jsfiddle.net/DerekL/Zdf9d/1/
Update
It will uncheck the first checkboxes when the Special checkbox is checked.
Pure JavaScript: http://jsfiddle.net/DerekL/Zdf9d/2/
More Updates
Here's the demo:
Pure JavaScript: http://jsfiddle.net/DerekL/Zdf9d/3/
jQuery: http://jsfiddle.net/DerekL/Zdf9d/4/
Little note: document.querySelectorAll works on all modern browsers and IE8+ including IE8. It is always better to use jQuery if you want to support IE6.

You can't use yes[] as an identifier in the Javascript, so you have to access the field using the name as a string:
document.mainForm["yes[]"]
This will not return a single element, it will return an array of elements. Use an index to access a specific element:
document.mainForm["yes[]"][0]
The value of the checkbox will always be the value property, regardless of whether the checkbox is selected or not. Use the checked property to find out if it's selected:
function spenable() {
var yes = document.mainForm["yes[]"][0].checked;
if (yes) {
alert("true");
} else {
alert("false");
};
}
To access the specific checkbox that was clicked, send the index of the checkbox in the event call:
<input class="cbox_yes" type="checkbox" name="yes[]" value="01.jpg" onclick="spenable(0);" /> OK
Use the index in the function:
function spenable(idx) {
var yes = document.mainForm["yes[]"][idx].checked;
var sp = document.mainForm["sp[]"][idx];
sp.disabled = !yes;
}

If you are open to using jQuery:
$('input[type="checkbox"]').click(function(){
var obj = $(this);
obj.next('.cbox_sp').attr({'disabled':(obj.is(':checked') ? false : 'disabled')});
});
This solution will assign an onclick event handler to all checkboxes and then check to see if the corresponding "special" checkbox should be disabled or not. It also sets the default checked state to true.
Working Example: http://jsfiddle.net/6YTqC/

Check if a checkbox is checked in JS

I am new to js and jquery. Currently, I have a form at form.php which contains a checkbox. When the user clicks submit, the form variables are sent to a form.js file where each value is checked to be null or not.
The form.js file works perfectly, however, for the checkbox nothing seems to happen. I have a feeling this is due to the way I have declared the variable.
The following is the code for the js file:
var email = $('#email').val();
var website = $('#website').val();
var CHECKBOX = $('CHECKBOX').val();
...
...
if (CHECKBOX.checked == FALSE){
var error = true;
$('#notchecked_error').fadeIn(500);
}else{
$('#notchecked_error').fadeOut(500);
}

Try using:
if ( $('#CHECKBOX').prop("checked") )
or:
if ( $('#CHECKBOX').is(":checked") )
Also, be sure your selector for the checkbox is correct.

I see two problems in your code. The first one is that the selector in your CHECKBOX assignation is faulty. It should be
var CHECKBOX = $('#CHECKBOX').val();
or
var CHECKBOX = $('input[type=checkbox]').val();
the second problem is that you are reading CHECKBOX.checked from the val() function, you need to read it from the checkbox itself.
if(CHECKBOX.checked)

$('input[type=checkbox]:checked') // If you have multiple checkboxes you can use this and loop through them to get additional info
$('#checkboxID:checked').length // To get one specific checkbox

`$('CHECKBOX').val();`
Will try to find an element with a tagname of CHECKBOX and return it's value. Presumably you want to reference the checkbox with an ID of CHECKBOX:
var CHECKBOX = $('#CHECKBOX');
To see if it's checked:
if (!CHECKBOX[0].checked) {
// CHECKBOX is not checked
}
You really should learn basic javascript before using jQuery. Usually validation is initiated from a form submit, which can give you are reference to the form. You can then reference all of the form elements as properties of the form, you don't need to create all of those jQuery objects. e.g. if you form is something like:
<form ... onsubmit="validate(this)"... >
<input type="checkbox" name="checkbox">
</form>
Then in your validate function:
function validate(form) {
if (!form.checkbox.checked) {
// the checkbox isn't checked
}
}
You can attach the listener dynamically if you wish.

JavaScript\JQuery - identifying if radio button value changed by click

I have a page that displays a list of records. The user can select the record status using radio buttons, e.g.:
<div id="record_653">
<label><input type="radio" name="status_653" value="new" checked/>new</label>
<label><input type="radio" name="status_653" value="skipped" />skipped</label>
<label><input type="radio" name="status_653" value="downloaded" />downloaded</label>
</div>
I am using JQuery to send the changes made by the user back to the server, where I use them to update the database. This is a simplified version of what I do:
$("#record_653").click(
function(event) {
var url = ...,
params = ...;
post(url,params);
});
The problem is that this code will create requests even if the user clicks the same button that was previously checked. What I actually want is the "on change" event, except its behavior in Internet Explorer is not very useful (e.g. here).
So I figure I somehow have to identify if the click event changed the value.
Is the old value stored somewhere (in the DOM? in the event?) so I could compare against it?
If not, how should I store the old value?

The old value is not stored someplace where you can query it, no. You will need to store the value yourself. You could use a javascript variable, a hidden input element, or jQuery's data() function.
EDIT
The jQuery data function provides access to a key-value-pair data structure as a way to store arbitrary data for a given element. The api looks like:
// store original value for an element
$(selector).data('key', value);
// retrieve original value for an element
var value = $(selector).data('key');
A more developed thought:
$(document).ready(function() {
// store original values on document ready
$(selector).each(function() {
var value = $(this).val();
$(this).data('original-value', value);
})
// later on, you might attach a click handler to the the option
// and want to determine if the value has actually changed or not.
$(selector).click(function() {
var currentValue = $(this).val();
var originalValue = $(this).data('original-value');
if (currentValue != originalValue) {
// do stuff.
// you might want to update the original value so future changes
// can be detected:
$(this).data('original-value', currentValue);
}
});
});

$('#record_653 input:radio').each(function() {
$(this).data('isChecked', $(this).is(':checked'));
$(this).click(function() {
if ( $(this).is(':checked') !== $(this).data('isChecked') ) {
// do changed action
} else {
$(this).data('isChecked', !$(this).data('isChecked') );
}
})
});
This was complicated to do in my head but I think you want something like this.

As was suggested by meder and Ken Browning, I ended up using JQuery's data() to store the previous value and check against it on every click.
Storing an "is checked" boolean for each input radio is one solution. However you need to maintain this value. So in the click event handler, in addition to changing the "is checked" of the current input, you need to find the input that was previously checked and change its "is checked" data to false.
What I chose to do instead was to store, in the parent element, the currently checked object. So my code looks something like:
$(document).ready(
function() {
// find the checked input and store it as "currChecked" for the record
$("#record_653").data("currChecked",
$(this).find("input:radio:checked")[0]);
// add the click event
$("#record_653").click( function(event) {
if ($(event.target).is("input:radio") &&
event.target !== $(this).data("currChecked"))
{
$(this).data("currChecked", event.target);
handleChangeEvent(event);
}
});
});
}
);
Thanks

I had the same problem, but with FF I managed to deal with it using the onchange event rather than the onclick.
This is exactly what I was looking for to deal with IE7. Works like a charm!
Thanks for the detailed solution!