JS获取checkbox的个数简单实例

var checkbox = document.getElementsByName("likes[]"); //此处通过此种方式才能获得多选框为数组。                                            //like为name = "like[]" , 获得时必须加上[]var checked_counts = 0;for(var i=0;i<checkbox.length;i++){if(checkbox[i].checked){     //被选中的checkboxchecked_counts++;}}alert(checked_counts);

function checkDate(){   var n = $("#cart_q_num").val();    var checkedCount=0;    var checkbox = document.getElementsByName("tie_in[]");   //alert(checkbox.length);   for(var i=0;i<checkbox.length ;i ++){    if(checkbox[i].checked){      checkedCount++;      }    }    //alert(checkedCount);    if(checkedCount>n){        alert("The quantity of the gifts should equal to the quantity of the sunglasses set.");       return false;    }else{     $("#free_pro_selected_num").html(checkedCount);    }}

<input type="checkbox" name="tie_in[]" value="1" onClick="return checkData()" />