Check if checkbox is checked with jQuery

Question

How can I check if a checkbox in a checkbox array is checked using the id of the checkbox array?

I am using the following code, but it always returns the count of checked checkboxes regardless of id.

function isCheckedById(id) {     alert(id);     var checked = $("input[@id=" + id + "]:checked").length;     alert(checked);      if (checked == 0) {         return false;     } else {         return true;     } } 

Answer 1

$('#' + id).is(":checked") 

That gets if the checkbox is checked.

For an array of checkboxes with the same name you can get the list of checked ones by:

var $boxes = $('input[name=thename]:checked'); 

Then to loop through them and see what's checked you can do:

$boxes.each(function(){     // Do stuff here with this }); 

To find how many are checked you can do:

$boxes.length; 

Answer 2

IDs must be unique in your document, meaning that you shouldn't do this:

<input type="checkbox" name="chk[]" id="chk[]" value="Apples" /> <input type="checkbox" name="chk[]" id="chk[]" value="Bananas" /> 

Instead, drop the ID, and then select them by name, or by a containing element:

<fieldset id="checkArray">     <input type="checkbox" name="chk[]" value="Apples" />      <input type="checkbox" name="chk[]" value="Bananas" /> </fieldset> 

And now the jQuery:

var atLeastOneIsChecked = $('#checkArray:checkbox:checked').length > 0; //there should be no space between identifier and selector  // or, without the container:  var atLeastOneIsChecked = $('input[name="chk[]"]:checked').length > 0;