Develop Reference

How change the css with the checkbox with different names?

Currently, I have multiple checkbox inputs with different names(checkit, checktype, checklog) assigned to the inputs.
What I want to do is to have each checkbox to change the color of the background when checked.
However, I dont know how I can assign each one of the checkbox to do some tasks without duplicating the following code ?If possible some examples or tips will be great! I would love to hear from you .
Should I remove name="checkit" if I want to make all the inputs do the same thing? What if I want them to do some slightly different things?
$('input[name="checkit"]').change(function () {
if ($(this).prop('checked')) {
$(this).parent().parent().addClass('alterBackground');
} else {
$(this).parent().parent().removeClass('alterBackground');
}
});

Add the following by , or give some class name to it
$('input[name="checkit"], input[name="checktype"], input[name="checklog"]').change(function () {
if ($(this).prop('checked')) {
$(this).parent().parent().addClass('alterBackground');
} else {
$(this).parent().parent().removeClass('alterBackground');
}
});

Don't use the name atrribute in jQuery and add a common class to each checkbox for a common functionality and access it with class selector in jQuery as shown below.
If you want to do something different with different checkboxes apart from this, then you can add more jQuery code for that specific input tag. It will not affect this code.
$('input.someClass').change(function () {
if ($(this).prop('checked')) {
$(this).parent().parent().addClass('alterBackground');
} else {
$(this).parent().parent().removeClass('alterBackground');
}
});

You can remove the name part from the selector and add selector for input[type='radio']. And if you want to add a bit different logic (I think you mean different classes), you can get the name of the current checked checkbox and use it to make your logic. Something like this
$('input[type="radio"]').change(function () {
var checkboxName = $(this).prop('name');
// if(checkboxName === .....)
});
Updated according to the comment
$('input[name="checkit"], input[name="checktype"], input[name="checklog"]').change(function () {
var checkboxName = $(this).prop('name');
// .............
});

$('input[type="checkbox"]').change(function () {
if ($(this).prop('checked')) {
$(this).parent().parent().addClass('alterBackground');
} else {
$(this).parent().parent().removeClass('alterBackground');
}
});

Use
$('input[type="checkbox"]')
instead of
$('input[name="checkit"]')

JS with select boxes

I am currently working on a bit of javascript that will execute when a checkbox is checked.
When the checkbox is checked, the form will display 2 more select boxes.
I've attempted something but i'm not very good with javascript, can someone take a look and lemme know where i'm going wrong?
$(document).ready(function() {
$("#repeat").change(function () {
if ($("#repeat").checked){
$("#numbers").slideDown();
} else{
$("#numbers").slideUp();
}
});
$("#numbers").hide();
$("#repeat").tigger("change");
});
And the id of the checkbox is repeat and id of one of the select boxes is numbers.

This part is not correct:
$("#repeat").checked
and should be
this.checked
So whole script:
$(document).ready(function () {
$("#repeat").change(function () {
if (this.checked) {
$("#numbers").slideDown();
} else {
$("#numbers").slideUp();
}
});
$("#numbers").hide();
$("#repeat").trigger("change"); // <--- trigger, not tigger
});
$("#repeat") is a jQuery instance object, it doesn't have a property checked. However this inside of change event handler refers to the HTMLSelectElement which has this property.
Also it's trigger not tigger.

Javascript: How to make only check box on-screen checked

I have a 200 rows table, which is paged into 20 pages (10 rows each page). Each of these row has a check box. I use jPage so all the table is still there, only get hidden by "display:none". I have written a function to select all check box (with some previous conditions attached), something like this:
$('#masterCbox').click(function () {
if($(this).is(':checked')) {
$('.childCbox').prop('checked', false);
$('.select-y').children('.childtd').children('.childCbox').prop('checked', true);
} else
$('.childCbox').prop('checked', false);
});
This will check all rows that have class="select-y".
However, it's required that only check boxes on-screen are going to be checked (check boxes belong to rows of displaying page). How am I going to accomplish that?

You can use the :visible selector in JQuery to see if something is visible or not.

Check if it's visible, and just check if it has a parent somewhere matching .select-y instead of all the children() stuff :
$('#masterCbox').click(function () {
if( this.checked ) {
$('.childCbox').prop('checked', false).filter(function() {
return $(this).is(':visible') && $(this).closest('.select-y').length;
}).prop('checked', true);
} else {
$('.childCbox').prop('checked', false);
}
});

You can apply a filter to check if your rows are visible :
$('.select-y').is(':visible').children('.childtd').children('.childCbox').prop('checked', true);

You can do this:
$('.select-y .childtd').children('.childCbox:visible').prop('checked', true);

How to select other checkbox when the last value is checked

Here an example of my checkbox list http://jsfiddle.net/YnM2f/
Let's say I check on G then A,B,C,D,E,F also automatic checked. How can i achieve my goals with jQuery?

First you need to get all the checkboxes based on which one is clicked. for this you need to get the parent nodes, siblings that are before it. Here is some code that will help you get there, but you'll need to work on it to make it work for you.
http://jsfiddle.net/urau8/
$("input:checkbox").on("click",function(){
if(this.checked)
$(this).parent().prevAll().each(function(){
$("input:checkbox",this).attr("checked",true);
});
});

This will check all checkboxes above a checkboxe that gets checked and uncheck all checkboxes above a checkbox that gets unchecked, given the checkbox layout that you've provided.
$('input:checkbox').click(function () {
var state = $(this).prop('checked');
var elements;
if (state) {
elements = $(this).parent().prevAll();
} else {
elements = $(this).parent().nextAll();
}
elements.each(function () {
$('input:checkbox', this).prop('checked',state);
});
});

$('input:checkbox').change(function(){
var $allParents = $(this).parent();
$allParents.prevAll().find('input').attr('checked', 'checked');
$allParents.nextAll().find('input').removeAttr('checked');
});
Try this

Well it's already been done five times, but this is what I did: http://jsfiddle.net/YnM2f/27/
$('input').click(function(){
if( $(this).is(':checked') ){
$(this).parent('p').prevAll().children('input').attr('checked',true)
}
})

Try something like this: http://jsfiddle.net/YnM2f/16/
It's a very specific solution (as in it will only work with "G"), but it should give you an idea for how to customize this code to meet your needs.
$('input:checkbox').filter(function(){
return (/ G/).test($(this).parent().text())
}).on('change', function() {
var gBox = $(this);
$('input:checkbox').prop('checked', $(gBox).prop('checked'));
});

Check/Uncheck checkbox with JavaScript

How can a checkbox be checked/unchecked using JavaScript?

Javascript:
// Check
document.getElementById("checkbox").checked = true;
// Uncheck
document.getElementById("checkbox").checked = false;
jQuery (1.6+):
// Check
$("#checkbox").prop("checked", true);
// Uncheck
$("#checkbox").prop("checked", false);
jQuery (1.5-):
// Check
$("#checkbox").attr("checked", true);
// Uncheck
$("#checkbox").attr("checked", false);

Important behaviour that has not yet been mentioned:
Programmatically setting the checked attribute, does not fire the change event of the checkbox.
See for yourself in this fiddle:
http://jsfiddle.net/fjaeger/L9z9t04p/4/
(Fiddle tested in Chrome 46, Firefox 41 and IE 11)
The click() method
Some day you might find yourself writing code, which relies on the event being fired. To make sure the event fires, call the click() method of the checkbox element, like this:
document.getElementById('checkbox').click();
However, this toggles the checked status of the checkbox, instead of specifically setting it to true or false. Remember that the change event should only fire, when the checked attribute actually changes.
It also applies to the jQuery way: setting the attribute using prop or attr, does not fire the change event.
Setting checked to a specific value
You could test the checked attribute, before calling the click() method. Example:
function toggle(checked) {
var elm = document.getElementById('checkbox');
if (checked != elm.checked) {
elm.click();
}
}
Read more about the click method here:
https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/click

to check:
document.getElementById("id-of-checkbox").checked = true;
to uncheck:
document.getElementById("id-of-checkbox").checked = false;

We can checked a particulate checkbox as,
$('id of the checkbox')[0].checked = true
and uncheck by ,
$('id of the checkbox')[0].checked = false

Try This:
//Check
document.getElementById('checkbox').setAttribute('checked', 'checked');
//UnCheck
document.getElementById('chk').removeAttribute('checked');

I would like to note, that setting the 'checked' attribute to a non-empty string leads to a checked box.
So if you set the 'checked' attribute to "false", the checkbox will be checked. I had to set the value to the empty string, null or the boolean value false in order to make sure the checkbox was not checked.

Using vanilla js:
//for one element:
document.querySelector('.myCheckBox').checked = true //will select the first matched element
document.querySelector('.myCheckBox').checked = false//will unselect the first matched element
//for multiple elements:
for (const checkbox of document.querySelectorAll('.myCheckBox')) {
//iterating over all matched elements
checkbox.checked = true //for selection
checkbox.checked = false //for unselection
}

function setCheckboxValue(checkbox,value) {
if (checkbox.checked!=value)
checkbox.click();
}

<script type="text/javascript">
$(document).ready(function () {
$('.selecctall').click(function (event) {
if (this.checked) {
$('.checkbox1').each(function () {
this.checked = true;
});
} else {
$('.checkbox1').each(function () {
this.checked = false;
});
}
});
});
</script>

For single check try
myCheckBox.checked=1
<input type="checkbox" id="myCheckBox"> Call to her
for multi try
document.querySelectorAll('.imChecked').forEach(c=> c.checked=1)
Buy wine: <input type="checkbox" class="imChecked"><br>
Play smooth-jazz music: <input type="checkbox"><br>
Shave: <input type="checkbox" class="imChecked"><br>

If, for some reason, you don't want to (or can't) run a .click() on the checkbox element, you can simply change its value directly via its .checked property (an IDL attribute of <input type="checkbox">).
Note that doing so does not fire the normally related event (change) so you'll need to manually fire it to have a complete solution that works with any related event handlers.
Here's a functional example in raw javascript (ES6):
class ButtonCheck {
constructor() {
let ourCheckBox = null;
this.ourCheckBox = document.querySelector('#checkboxID');
let checkBoxButton = null;
this.checkBoxButton = document.querySelector('#checkboxID+button[aria-label="checkboxID"]');
let checkEvent = new Event('change');
this.checkBoxButton.addEventListener('click', function() {
let checkBox = this.ourCheckBox;
//toggle the checkbox: invert its state!
checkBox.checked = !checkBox.checked;
//let other things know the checkbox changed
checkBox.dispatchEvent(checkEvent);
}.bind(this), true);
this.eventHandler = function(e) {
document.querySelector('.checkboxfeedback').insertAdjacentHTML('beforeend', '<br />Event occurred on checkbox! Type: ' + e.type + ' checkbox state now: ' + this.ourCheckBox.checked);
}
//demonstration: we will see change events regardless of whether the checkbox is clicked or the button
this.ourCheckBox.addEventListener('change', function(e) {
this.eventHandler(e);
}.bind(this), true);
//demonstration: if we bind a click handler only to the checkbox, we only see clicks from the checkbox
this.ourCheckBox.addEventListener('click', function(e) {
this.eventHandler(e);
}.bind(this), true);
}
}
var init = function() {
const checkIt = new ButtonCheck();
}
if (document.readyState != 'loading') {
init;
} else {
document.addEventListener('DOMContentLoaded', init);
}
<input type="checkbox" id="checkboxID" />
<button aria-label="checkboxID">Change the checkbox!</button>
<div class="checkboxfeedback">No changes yet!</div>
If you run this and click on both the checkbox and the button you should get a sense of how this works.
Note that I used document.querySelector for brevity/simplicity, but this could easily be built out to either have a given ID passed to the constructor, or it could apply to all buttons that act as aria-labels for a checkbox (note that I didn't bother setting an id on the button and giving the checkbox an aria-labelledby, which should be done if using this method) or any number of other ways to expand this. The last two addEventListeners are just to demo how it works.

I agree with the current answers, but in my case it does not work, I hope this code help someone in the future:
// check
$('#checkbox_id').click()