Jquery - 检查是否至少选中了一个复选框

Question

我有以下HTML表单,它可以有很多复选框.单击提交按钮时,我希望用户获取javascript警报以检查至少一个复选框(如果没有选中).使用Jquery有一种简单的方法吗？

<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>

Answer 1

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

Answer 2

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

Answer 3

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

Answer 4

$("#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 5

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

如果选中至少一个或多个复选框,则is(':checked')将返回true.

Answer 6

$('#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>