Jquery - check if atleast one checkbox is checked

Question

All,

I have the following HTML form and it can have many checkboxes. When the submit button is clicked, I want the user to get a javascript alert to check atleast one checkbox if none are checked. Is there an easy way to do this using Jquery?

<form name = "frmTest" id="frmTest">
<input type="checkbox" value="true" checked="true" name="chk[120]">
<input type="checkbox" value="true" checked="true" name="chk[128]">
<input type="checkbox" name="chk[130]">
<input type="checkbox" name="chk[143]">
<input type="submit" name="btnsubmit" value="Submit">
</form>

Thanks

Answer 1

$('#frmTest input:checked').length > 0

Answer 2

$("#frmTest").submit(function(){
    var checked = $("#frmText input:checked").length > 0;
    if (!checked){
        alert("Please check at least one checkbox");
        return false;
    }
});

Answer 3

if(jQuery('#frmTest input[type=checkbox]:checked').length) { … }

Answer 4

$('#frmTest').submit(function(){
    if(!$('#frmTest input[type="checkbox"]').is(':checked')){
      alert("Please check at least one.");
      return false;
    }
});

is(':checked') will return true if at least one or more of the checkboxes are checked.