How to check the correct selection of a flag if all the flags have the same name?

Question

Hello everyone. I have a group of flags with the same name to get an array of a single variable when it is sent on the server server, e.g. L

<input type="checkbox" name="midlevelusers[]" value="1">
<input type="checkbox" name="midlevelusers[]" value="1">
<input type="checkbox" name="midlevelusers[]" value="1">
<input type="checkbox" name="midlevelusers[]" value="1">

I need javascript validation to check if any checkbox is selected?

Thanks and Regards

NOTE. I need javascript validation

Answer 1

<form name="myform" method="POST" action="" onsubmit="return checkTheBox();">
  <input type="checkbox" name="midlevelusers[]" value="1" /> 1 &nbsp;&nbsp;
  <input type="checkbox" name="midlevelusers[]" value="2" /> 2 &nbsp;&nbsp;
  <input type="checkbox" name="midlevelusers[]" value="3" /> 3 &nbsp;&nbsp;
  <input type="checkbox" name="midlevelusers[]" value="4" /> 4 &nbsp;&nbsp;
  <input type="checkbox" name="midlevelusers[]" value="5" /> 5 &nbsp;&nbsp;
  <input type="submit" value="Submit Form" />
</form>

<script type="text/javascript">
  function checkTheBox() {
    var flag = 0;
    for (var i = 0; i< 5; i++) {
      if(document.myform["midlevelusers[]"][i].checked){
        flag ++;
      }
    }
    if (flag != 1) {
      alert ("You must check one and only one checkbox!");
      return false;
    }
    return true;
  }
</script>

Answer 2

You can access the DOM elements and check their property checked. For instance:

var list, index, item, checkedCount;

checkedCount = 0;
list = document.getElementsByTagName('input');
for (index = 0; index < list.length; ++index) {
    item = list[index];
    if (item.getAttribute('type') === "checkbox"
        && item.checked
        && item.name === "midlevelusers[]") {
        ++checkedCount;
    }
 }

Living example

, . (, , , form), , ( var, form = list = /):

var form, list, index, item, checkedCount;

checkedCount = 0;
form = document.getElementById('theForm');
list = form.getElementsByTagName('input');
for (index = 0; index < list.length; ++index) {
    item = list[index];
    if (item.getAttribute('type') === "checkbox"
        && item.checked
        && item.name === "midlevelusers[]") {
        ++checkedCount;
    }
 }

---

. , , FWIW , jQuery, Prototype, YUI, Closure, . , jQuery:

var checkedCount = $("input[type=checkbox][name^=midlevelusers]:checked").length;

, .

Answer 3

id

<input type="checkbox" name="midlevelusers[]" id="mlu1" value="1">
<input type="checkbox" name="midlevelusers[]" id="mlu2" value="2">
<input type="checkbox" name="midlevelusers[]" id="mlu3" value="3">
<input type="checkbox" name="midlevelusers[]" id="mlu4" value="4">

for (var i=1;i<5;i++){
  var el = document.getElementById('mlu'+i);
  if (el.checked) { /* do something */}
}

Answer 4

,

function validate() {
    var chk = document.getElementsByName('midlevelusers[]')
    var len = chk.length

    for(i=0;i<len;i++)
    {
         if(chk[i].checked){
        return true;
          }
    }
    return false;
    }

Answer 5

, .

function isChecked(checkboxarray){
    for (counter = 0; counter < checkboxarray.length; counter++){
        if (checkboxarray[counter].checked){
            alert("Checkbox has at least one checked");
        else{
            alert("None checked");
        }

You need to add a little more to do what you really want to do, but it will help you on the right track, I think!

Answer 6

You can use jQueryand do it as follows:

if($('input[name="light[]"]:checked').length < 1){
            alert("Please enter the light conditions");
}