Develop Reference

ko binding for checkbox: change 'checked' attr from code not change the observable field

I have checkbox at html that is binding to observable-field (field of breeze entity).
<input id="chk1" type="checkbox" data-bind="checked: data().isBirthday"/>
The binding works well from the tow sides:
When I write at code:
data().isBirthday(true);
the checkbox become checked.
and when I write at code
data().isBirthday(false);
the checkbox become unchecked.
And when I choose the checkbox by clicking with mouse - the observable field gets value of true. (Or when I unchecked by mouse - it gets value of false).
sometime, I need to change the checked attribute of the checkbox by code, specifically by retrive checkbox with jquery.
(I cannot do it by the observable field becouse of any reasons).
I do:
var control = $('#chk1')[0];
control.checked = false;
but this not change the value of the binded observable-field. It continue holding true value.
I tried to triiger the change event:
$(control).change()
It didn't help.
So, what should I do?
Here is an example:
https://jsfiddle.net/kevinvanlierde/72972fwt/4/

Can we see the html code?
Try $('#chk1').prop("checked", false);

Foundation checkbox value error

I'm using the Foundation 4 framework and I added a custom form into my page.
HTML:
<label for="checkbox2">
<input type="checkbox" id="checkbox2" style="display: none;">
<span class="custom checkbox"></span> <p> CHECKBOX TEST</p>
</label>
JS:
if($('#checkbox2').is(":checked")){
isnewsletter = 1;
} else {
isnewsletter = 0;
}
and even this
newsletter = $('#checkbox2').val(),
isn't working.
How can I check, if my checkbox is checked?

$('#checkbox2').change(function(){
if($(this).is(":checked")){
console.log(1);
} else {
console.log(0);
}
});

First checking works fine. If you add checked="checked" to your checkbox isnewsletter will be 1.
P.S. You don't mention any other way how you tick checkbox in your program. Your checkbox is not displayed on the page, so you cannot tick it manually.

The question isn't quite clear whether OP wants to check if checkbox is :checked on change, at any random moment during interaction on a page, or on validation using the Foundation 4 Abide library. I've run into issues with the custom form and toggling hidden fields, as well as validating hidden fields, and the custom form doesn't help. However, I've worked around it, but those are different questions.
The "custom" form does by default hide the input and create a span after it that gets the class "checked", and the property on the hidden checkbox doesn't visually appear in Chrome's developer toolbar (I haven't checked FireBug to see if that property appears). However, if you write a code based check of the property of the checkbox, it will return 'true':
$("#checkbox2").change(function() {
console.log($(this).is(":checked"));
console.log($(this).prop('checked'));
// set up if using either method above, your choice.
if( $(this).prop('checked')) {
// do stuff
}
});
Or you can check the span.checkbox.custom directly after the input for the class "checked":
$("#checkbox2").change(function() {
console.log($(this).next().hasClass("checked"));
// set up if statement using that logic above:
if($(this).next().hasClass("checked") ) {
// do stuff
}
});
Use the same logic to check whether the checkbox is checked at any point, just don't bother with the .change() function. These will return true if the box is checked:
$("#checkbox2").next().hasClass("checked");
$("#checkbox2").is(":checked");
$("#checkbox2").prop("checked");
Foundation 4 didn't have validation built into Abide, you'd have to add it in.
This requires adjusting Abide.
I answered that question here.

Getting only the list of checkboxes from a collection of checkboxes for which status is changed(checked or unchecked) using jquery

I have a table with multiple rows and each row has a checkbox which is in either checked or unchecked state. The user can check or uncheck few of the checkboxes and hit the submit button to save their changes.
Is their any way to get only the list of checkboxes whose original state changed(from checked to unchecked or unchecked to checked)?
If this is possible then I will be able to provide the users with a single button to update or else I may have to give a button for each row to update.
I am also thinking of updating via ajax as soon as the status changes for each checkbox, but I prefer to make one server call by updating all at once.
Any information regarding this issue is very much appreciated.
Thank you!

If the checked attribute is set in the markup you can do this by using .attr() and .prop()
html
<input type="checkbox" checked="checked" />
<input type="checkbox" />
js
var changedInputs = $("input").filter(function() {
var input = $(this),
checked = (input.attr("checked") || "") === "checked";
return (checked !== input.prop("checked"));
});
console.log(changedInputs);
Example

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/

Using depends with the jQuery Validation plugin

I've got a form with a bunch of textboxes that are disabled by default, then enabled by use of a checkbox next to each one.
When enabled, the values in these textboxes are required to be a valid number, but when disabled they don't need a value (obviously). I'm using the jQuery Validation plugin to do this validation, but it doesn't seem to be doing what I expect.
When I click the checkbox and disable the textbox, I still get the invalid field error despite the depends clause I've added to the rules (see code below). Oddly, what actually happens is that the error message shows for a split second then goes away.
Here is a sample of the list of checkboxes & textboxes:
<ul id="ItemList">
<li>
<label for="OneSelected">One</label><input id="OneSelected" name="OneSelected" type="checkbox" value="true" />
<input name="OneSelected" type="hidden" value="false" />
<input disabled="disabled" id="OneValue" name="OneValue" type="text" />
</li>
<li>
<label for="TwoSelected">Two</label><input id="TwoSelected" name="TwoSelected" type="checkbox" value="true" />
<input name="TwoSelected" type="hidden" value="false" />
<input disabled="disabled" id="TwoValue" name="TwoValue" type="text" />
</li>
</ul>
And here is the jQuery code I'm using
//Wire up the click event on the checkbox
jQuery('#ItemList :checkbox').click(function(event) {
var textBox = jQuery(this).siblings(':text');
textBox.valid();
if (!jQuery(this).attr("checked")) {
textBox.attr('disabled', 'disabled');
textBox.val('');
} else {
textBox.removeAttr('disabled');
textBox[0].focus();
}
});
//Add the rules to each textbox
jQuery('#ItemList :text').each(function(e) {
jQuery(this).rules('add', {
required: {
depends: function(element) {
return jQuery(element).siblings(':checkbox').attr('checked');
}
},
number: {
depends: function(element) {
return jQuery(element).siblings(':checkbox').attr('checked');
}
}
});
});
Ignore the hidden field in each li it's there because I'm using asp.net MVC's Html.Checkbox method.

Using the "ignore" option (http://docs.jquery.com/Plugins/Validation/validate#toptions) might be the easiest way for you to deal with this. Depends on what else you have on the form. For i.e. you wouldn't filter on disabled items if you had other controls that were disabled but you still needed to validate for some reason. However, if that route doesn't work, using an additional class to filter on (adding and removing with your checkboxes) should get you to where you want to go, but easier.
I.e.
$('form').validate({
ignore: ":disabled",
...
});

Usually when doing this, I skip 'depends' and just use the required jQuery Validate rule and let it handle the checking based on the given selector, as opposed to splitting the logic between the validate rules and the checkbox click handler. I put together a quick demo of how I accomplish this, using your markup.
Really, it boils down to required:'#OneSelected:checked'. This makes the field in question required only if the expression is true. In the demo, if you submit the page right away, it works, but as you check boxes, the form is unable to submit until the checked fields are filled with some input. You could still put a .valid() call in the checkbox click handler if you want the entire form to validate upon click.
(Also, I shortened up your checkbox toggling a bit, making use of jQuery's wonderful chaining feature, though your "caching" to textBox is just as effective.)

Depends parameter is not working correctly, I suppose documentation is out of date.
I managed to get this working like this:
required : function(){ return $("#register").hasClass("open")}

Following #Collin Allen answer:
The problem is that if you uncheck a checkbox when it's error message is visible, the error message doesn't go away.
I have solved it by removing the error message when disabling the field.
Take Collin's demo and make the following changes to the enable/disable process:
jQuery('#ItemList :checkbox').click(function()
{
var jqTxb = $(this).siblings(':text')
if ($(this).attr('checked'))
{
jqTxb.removeAttr('disabled').focus();
}
else
{
jqTxb.attr('disabled', 'disabled').val('');
var obj = getErrorMsgObj(jqTxb, "");
jqTxb.closest("form").validate().showErrors(obj);
}
});
function getErrorMsgObj(jqField, msg)
{
var obj = {};
var nameOfField = jqField.attr("name");
obj[nameOfField] = msg;
return obj;
}
You can see I guts remove the error message from the field when disabling it
And if you are worrying about $("form").validate(), Don't!
It doesn't revalidate the form it just returns the API object of the jQuery validation.

I don't know if this is what you were going for... but wouldn't changing .required to .wasReq (as a placeholder to differentiate this from one which maybe wouldn't be required) on checking the box do the same thing? If it's not checked, the field isn't required--you could also removeClass(number) to eliminate the error there.
To the best of my knowledge, even if a field is disabled, rules applied to it are still, well, applied. Alternatively, you could always try this...
// Removes all values from disabled fields upon submit
$(form).submit(function() {
$(input[type=text][disabled=disabled]).val();
});

I havent tried the validator plugin, but the fact that the message shows for a splitsecond sounds to me like a double bind, how do you call your binders? If you bind in a function try unbinding just before you start, like so:
$('#ItemList :checkbox').unbind("click");
...Rest of code here...

Shouldn't validate the field after disabling/enabling?
jQuery('#ItemList :checkbox').click(function(event) {
var textBox = jQuery(this).siblings(':text');
if (!jQuery(this).attr("checked")) {
textBox.attr('disabled', 'disabled');
textBox.val('');
} else {
textBox.removeAttr('disabled');
textBox[0].focus();
}
textBox.valid();
});

I had the exact same problem.
I solved this by having the radio-button change event handler call valid() on the entire form.
Worked perfect. The other solutions above didn't work for me.