Can I use jQuery to check whether at least one checkbox is checked?

Question

I have the following HTML form which can have many checkboxes. When the submit button is clicked, I want the user to get a javascript alert to check at least one checkbox if

Answer 1

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

Answer 2

$("#show").click(function() {
    var count_checked = $("[name='chk[]']:checked").length; // count the checked rows
        if(count_checked == 0) 
        {
            alert("Please select any record to delete.");
            return false;
        }
        if(count_checked == 1) {
            alert("Record Selected:"+count_checked);

        } else {
            alert("Record Selected:"+count_checked);
          }
});

Answer 3

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

Answer 4

$('#fm_submit').submit(function(e){
    e.preventDefault();
    var ck_box = $('input[type="checkbox"]:checked').length;
    
    // return in firefox or chrome console 
    // the number of checkbox checked
    console.log(ck_box); 

    if(ck_box > 0){
      alert(ck_box);
    } 
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<form name = "frmTest[]" id="fm_submit">
  <input type="checkbox" value="true" checked="true" >
  <input type="checkbox" value="true" checked="true" >
  <input type="checkbox" >
  <input type="checkbox" >
  <input type="submit" id="fm_submit" name="fm_submit" value="Submit">
</form>
<div class="container"></div>

Answer 5

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

Answer 6

$('#frmTest').submit(function(){
    if(!$('#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.