jQuery: Test if checkbox is NOT checked

One reliable way I use is:

if($("#checkSurfaceEnvironment-1").prop('checked') == true){
    //do something
}

If you want to iterate over checked elements use the parent element

$("#parentId").find("checkbox").each(function(){
    if ($(this).prop('checked')==true){ 
        //do something
    }
});

More info:

This works well because all checkboxes have a property checked which stores the actual state of the checkbox. If you wish you can inspect the page and try to check and uncheck a checkbox, and you will notice the attribute "checked" (if present) will remain the same. This attribute only represents the initial state of the checkbox, and not the current state. The current state is stored in the property checked of the dom element for that checkbox.

See Properties and Attributes in HTML

if (!$("#checkSurfaceEnvironment-1").is(":checked")) {
    // do something if the checkbox is NOT checked
}

You can also use either jQuery .not() method or :not() selector:

if ($('#checkSurfaceEnvironment').not(':checked').length) {
    // do stuff for not selected
}

JSFiddle Example

Additional Notes

From the jQuery API documentation for the :not() selector:

The .not() method will end up providing you with more readable selections than pushing complex selectors or variables into a :not() selector filter. In most cases, it is a better choice.

An alternative way:

Here is a working example and here is the code, you should also use prop.

$('input[type="checkbox"]').mouseenter(function() { 
    if ($(this).is(':checked')) {
        //$(this).prop('checked',false);
        alert("is checked");
    } else {
         //$(this).prop('checked',true);
        alert("not checked");
    }
});​

I commented out the way to toggle the checked attribute.

I think the easiest way (with jQuery) to check if checkbox is checked or NOT is:

if 'checked':

if ($(this).is(':checked')) {
// I'm checked let's do something
}

if NOT 'checked':

if (!$(this).is(':checked')) {
// I'm NOT checked let's do something
}

if ( $("#checkSurfaceEnvironment-1").is(":checked") && $("#checkSurfaceEnvironment-2").not(":checked") )

I was looking for a more direct implementation like avijendr suggested.

I had a little trouble with his/her syntax, but I got this to work:

if ($('.user-forms input[id*="chkPrint"]:not(:checked)').length > 0)

In my case, I had a table with a class user-forms, and I was checking if any of the checkboxes that had the string checkPrint in their id were unchecked.

Here I have a snippet for this question.

$(function(){ $("#buttoncheck").click(function(){ if($('[type="checkbox"]').is(":checked")){ $('.checkboxStatus').html("Congratulations! "+$('[type="checkbox"]:checked').length+" checkbox checked"); }else{ $('.checkboxStatus').html("Sorry! Checkbox is not checked"); } return false; }) });

To do it with .attr() like you have, to see if it's checked it would be .attr("checked", "checked"), and if it isn't it would be .attr("checked") == undefined

Return true if all checbox are checked in a div

function all_checked (id_div){
 all_checked = true;

 $(id_div+' input[type="checkbox"]').each(function() { 
    all_checked = all_checked && $('this').prop('checked');
 }

 return all_checked;
}

Simple and easy to check or unchecked condition

<input type="checkbox" id="ev-click" name="" value="" >

<script>
    $( "#ev-click" ).click(function() {
        if(this.checked){
            alert('checked');
        }
        if(!this.checked){
            alert('Unchecked');
        }
    });
</script>

try this one

if ($("#checkSurfaceEnvironment-1:checked").length>0) {
    //your code in case of NOT checked
}

In Above code selecting the element by Id (#checkSurfaceEnvironment-1) then filter out it's checked state by (:checked) filter.

It will return array of checked element object. If there any object exists in the array then if condition will be satisfied.

There are two way you can check condition.

if ($("#checkSurfaceEnvironment-1").is(":checked")) {
    // Put your code here if checkbox is checked
}

OR you can use this one also

if($("#checkSurfaceEnvironment-1").prop('checked') == true){
    // Put your code here if checkbox is checked
}

I hope this is useful for you.

Here is the simplest way given

 <script type="text/javascript">

        $(document).ready(function () {
            $("#chk_selall").change("click", function () {

                if (this.checked)
                {
                    //do something
                }
                if (!this.checked)
                {
                    //do something

                }

            });

        });

    </script>

I used this and in worked for me!

$("checkbox selector").click(function() {
    if($(this).prop('checked')==true){
       do what you need!
    }
});

I know this has already been answered, but still, this is a good way to do it:

if ($("#checkbox").is(":checked")==false) {
    //Do stuff here like: $(".span").html("<span>Lorem</span>");
}

if($("#checkbox1").prop('checked') == false){
    alert('checkbox is not checked');
    //do something
}
else
{ 
    alert('checkbox is checked');
}

$("#chkFruits_0,#chkFruits_1,#chkFruits_2,#chkFruits_3,#chkFruits_4").change(function () {
        var item = $("#chkFruits_0,#chkFruits_1,#chkFruits_2,#chkFruits_3,#chkFruits_4");
    if (item.is(":checked")==true) {
        //execute your code here
    }

    else if (item.is(":not(:checked)"))
    {
        //execute your code here
    }

});