javascript how - Setting “checked” for a checkbox with jQuery?




is if (25)

This is probably the shortest and easiest solution:

$(".myCheckBox")[0].checked = true;

or

$(".myCheckBox")[0].checked = false;

Even shorter would be:

$(".myCheckBox")[0].checked = !0;
$(".myCheckBox")[0].checked = !1;

Here is a jsFiddle as well.

I'd like to do something like this to tick a checkbox using jQuery:

$(".myCheckBox").checked(true);

or

$(".myCheckBox").selected(true);

Does such a thing exist?


When you checked a checkbox like;

$('.className').attr('checked', 'checked')

it might not be enough. You should also call the function below;

$('.className').prop('checked', 'true')

Especially when you removed the checkbox checked attribute.


We can use elementObject with jQuery for getting the attribute checked:

$(objectElement).attr('checked');

We can use this for all jQuery versions without any error.

Update: Jquery 1.6+ has the new prop method which replaces attr, e.g.:

$(objectElement).prop('checked');

I couldn't get it working using:

$("#cb").prop('checked', 'true');
$("#cb").prop('checked', 'false');

Both true and false would check the checkbox. What worked for me was:

$("#cb").prop('checked', 'true'); // For checking
$("#cb").prop('checked', '');     // For unchecking

You can do

$('.myCheckbox').attr('checked',true) //Standards compliant

or

$("form #mycheckbox").attr('checked', true)

If you have custom code in the onclick event for the checkbox that you want to fire, use this one instead:

$("#mycheckbox").click();

You can uncheck by removing the attribute entirely:

$('.myCheckbox').removeAttr('checked')

You can check all checkboxes like this:

$(".myCheckbox").each(function(){
    $("#mycheckbox").click()
});

As @livefree75 said:

jQuery 1.5.x and below

You can also extend the $.fn object with new methods:

(function($)  {
   $.fn.extend({
      check : function()  {
         return this.filter(":radio, :checkbox").attr("checked", true);
      },
      uncheck : function()  {
         return this.filter(":radio, :checkbox").removeAttr("checked");
      }
   });
}(jQuery));

But in new versions of jQuery, we have to use something like this:

jQuery 1.6+

    (function($)  {
       $.fn.extend({
          check : function()  {
             return this.filter(":radio, :checkbox").prop("checked", true);
          },
          uncheck : function()  {
             return this.filter(":radio, :checkbox").prop("checked",false);
          }
       });
    }(jQuery));

Then you can just do:

    $(":checkbox").check();
    $(":checkbox").uncheck();

To check and uncheck

$('.myCheckbox').prop('checked', true);
$('.myCheckbox').prop('checked', false);

Here is a way to do it without jQuery

function addOrAttachListener(el, type, listener, useCapture) {
  if (el.addEventListener) {
    el.addEventListener(type, listener, useCapture);
  } else if (el.attachEvent) {
    el.attachEvent("on" + type, listener);
  }
};

addOrAttachListener(window, "load", function() {
  var cbElem = document.getElementById("cb");
  var rcbElem = document.getElementById("rcb");
  addOrAttachListener(cbElem, "click", function() {
    rcbElem.checked = cbElem.checked;
  }, false);
}, false);
<label>Click Me!
  <input id="cb" type="checkbox" />
</label>
<label>Reflection:
  <input id="rcb" type="checkbox" />
</label>

Here is code for checked and unchecked with a button:

var set=1;
var unset=0;
jQuery( function() {
    $( '.checkAll' ).live('click', function() {
        $( '.cb-element' ).each(function () {
            if(set==1){ $( '.cb-element' ).attr('checked', true) unset=0; }
            if(set==0){ $( '.cb-element' ).attr('checked', false); unset=1; }
        });
        set=unset;
    });
});

Update: Here is the same code block using the newer Jquery 1.6+ prop method, which replaces attr:

var set=1;
var unset=0;
jQuery( function() {
    $( '.checkAll' ).live('click', function() {
        $( '.cb-element' ).each(function () {
            if(set==1){ $( '.cb-element' ).prop('checked', true) unset=0; }
            if(set==0){ $( '.cb-element' ).prop('checked', false); unset=1; }
        });
        set=unset;
    });
});

If you are using PhoneGap doing application development, and you have a value on the button that you want to show instantly, remember to do this

$('span.ui-[controlname]',$('[id]')).text("the value");

I found that without the span, the interface will not update no matter what you do.


Try this:

$('#checkboxid').get(0).checked = true;  //For checking

$('#checkboxid').get(0).checked = false; //For unchecking

To check a checkbox using jQuery 1.6 or higher just do this:

checkbox.prop('checked', true);

To uncheck, use:

checkbox.prop('checked', false);

Here' s what I like to use to toggle a checkbox using jQuery:

checkbox.prop('checked', !checkbox.prop('checked'));

If you're using jQuery 1.5 or lower:

checkbox.attr('checked', true);

To uncheck, use:

checkbox.attr('checked', false);

Plain JavaScript is very simple and much less overhead:

var elements = document.getElementsByClassName('myCheckBox');
for(var i = 0; i < elements.length; i++)
{
    elements[i].checked = true;
}

Example here


This is the correct way of checking and unchecking checkboxes with jQuery, as it is cross-platform standard, and will allow form reposts.

$('.myCheckBox').each(function(){ this.checked = true; });

$('.myCheckBox').each(function(){ this.checked = false; });

By doing this, you are using JavaScript standards for checking and unchecking checkboxes, so any browser that properly implements the "checked" property of the checkbox element will run this code flawlessly. This should be all major browsers, but I am unable to test previous to Internet Explorer 9.

The Problem (jQuery 1.6):

Once a user clicks on a checkbox, that checkbox stops responding to the "checked" attribute changes.

Here is an example of the checkbox attribute failing to do the job after someone has clicked the checkbox (this happens in Chrome).

Fiddle

The Solution:

By using JavaScript's "checked" property on the DOM elements, we are able to solve the problem directly, instead of trying to manipulate the DOM into doing what we want it to do.

Fiddle

This plugin will alter the checked property of any elements selected by jQuery, and successfully check and uncheck checkboxes under all circumstances. So, while this may seem like an over-bearing solution, it will make your site's user experience better, and help prevent user frustration.

(function( $ ) {
    $.fn.checked = function(value) {
        if(value === true || value === false) {
            // Set the value of the checkbox
            $(this).each(function(){ this.checked = value; });
        } 
        else if(value === undefined || value === 'toggle') {
            // Toggle the checkbox
            $(this).each(function(){ this.checked = !this.checked; });
        }

        return this;
    };
})( jQuery );

Alternatively, if you do not want to use a plugin, you can use the following code snippets:

// Check
$(':checkbox').prop('checked', true);

// Un-check
$(':checkbox').prop('checked', false);

// Toggle
$(':checkbox').prop('checked', function (i, value) {
    return !value;
});

Be aware of memory leaks in Internet Explorer prior to Internet Explorer 9, as the jQuery documentation states:

In Internet Explorer prior to version 9, using .prop() to set a DOM element property to anything other than a simple primitive value (number, string, or boolean) can cause memory leaks if the property is not removed (using .removeProp()) before the DOM element is removed from the document. To safely set values on DOM objects without memory leaks, use .data().


jQuery 1.6+

Use the new .prop() method:

$('.myCheckbox').prop('checked', true);
$('.myCheckbox').prop('checked', false);

jQuery 1.5.x and below

The .prop() method is not available, so you need to use .attr().

$('.myCheckbox').attr('checked', true);
$('.myCheckbox').attr('checked', false);

Note that this is the approach used by jQuery's unit tests prior to version 1.6 and is preferable to using

$('.myCheckbox').removeAttr('checked');

since the latter will, if the box was initially checked, change the behaviour of a call to .reset() on any form that contains it - a subtle but probably unwelcome behaviour change.

For more context, some incomplete discussion of the changes to the handling of the checked attribute/property in the transition from 1.5.x to 1.6 can be found in the version 1.6 release notes and the Attributes vs. Properties section of the .prop() documentation.

Any version of jQuery

If you're working with just one element, you can always just modify the HTMLInputElement's .checked property:

$('.myCheckbox')[0].checked = true;
$('.myCheckbox')[0].checked = false;

The benefit to using the .prop() and .attr() methods instead of this is that they will operate on all matched elements.


To check a checkbox you should use

 $('.myCheckbox').attr('checked',true);

or

 $('.myCheckbox').attr('checked','checked');

and to uncheck a check box you should always set it to false:

 $('.myCheckbox').attr('checked',false);

If you do

  $('.myCheckbox').removeAttr('checked')

it removes the attribute all together and therefore you will not be able to reset the form.

BAD DEMO jQuery 1.6. I think this is broken. For 1.6 I am going to make a new post on that.

NEW WORKING DEMO jQuery 1.5.2 works in Chrome.

Both demos use

$('#tc').click(function() {
    if ( $('#myCheckbox').attr('checked')) {
        $('#myCheckbox').attr('checked', false);
    } else {
        $('#myCheckbox').attr('checked', 'checked');
    }
});

Another possible solution:

    var c = $("#checkboxid");
    if (c.is(":checked")) {
         $('#checkboxid').prop('checked', false);
    } else {
         $('#checkboxid').prop('checked', true);
    }

I'm missing the solution. I'll always use:

if ($('#myCheckBox:checked').val() !== undefined)
{
    //Checked
}
else
{
    //Not checked
}

In jQuery,

if($("#checkboxId").is(':checked')){
    alert("Checked");
}

or

if($("#checkboxId").attr('checked')==true){
    alert("Checked");
}

In JavaScript,

if (document.getElementById("checkboxID").checked){
    alert("Checked");
}

Use:

$(".myCheckbox").attr('checked', true); // Deprecated
$(".myCheckbox").prop('checked', true);

And if you want to check if a checkbox is checked or not:

$('.myCheckbox').is(':checked');

Here is the code and demo for how to check multiple check boxes...

http://jsfiddle.net/tamilmani/z8TTt/

$("#check").on("click", function () {

    var chk = document.getElementById('check').checked;
    var arr = document.getElementsByTagName("input");

    if (chk) {
        for (var i in arr) {
            if (arr[i].name == 'check') arr[i].checked = true;
        }
    } else {
        for (var i in arr) {
            if (arr[i].name == 'check') arr[i].checked = false;
        }
    }
});

Assuming that the question is...

How do I check a checkbox-set BY VALUE?

Remember that in a typical checkbox set, all input tags have the same name, they differ by the attribute value: there are no ID for each input of the set.

Xian's answer can be extended with a more specific selector, using the following line of code:

$("input.myclass[name='myname'][value='the_value']").prop("checked", true);

This selects elements that have the specified attribute with a value containing the given substring "ckbItem":

$('input[name *= ckbItem]').prop('checked', true);

It will select all elements that contain ckbItem in its name attribute.


$("selector") give an object which has length data. If there are elements as you define in selector, you will get them from the object. So if you check it's length you allready can find, is there any element exists. In javascript 0 == false also null == false . If you not get 0 your codes will run.

if($("selector").length){
   //code in the case
} 




javascript jquery checkbox selected checked