[removed] Unchecking all checkboxes

Question

I have problem dealing with unchecking all checkboxes. When I click on a toggle all checkbox, it could check all checkboxes. But if I uncheck the toggle all checkbox, nothin

Answer 1

You could also make it a Boolean Variable.

<script>
var isAllCheck = new Boolean(false);
function togglecheckboxes(cn){

var cbarray = document.getElementsByName(cn);
for(var i = 0; i < cbarray.length; i++){

    if(isAllCheck){ //and then you could make this shorter.
        cbarray[i].checked = true;
        //alert( "it is false" );
    }else{ 
        cbarray[i].removeAttribute("checked");
        //alert( "it is true" );
    }
}   
isAllCheck = !isAllCheck;   
}
</script>

Answer 2

Try this

    <script>
var isAllCheck = false;
function togglecheckboxes(master,cn){

    var cbarray = document.getElementsByName(cn);
    for(var i = 0; i < cbarray.length; i++){

        if( isAllCheck == false ){
            cbarray[i].checked = true;
            //alert( "it is false" );
        }else{ 
            cbarray[i].checked = false;
            //alert( "it is true" );
        }
}   
isAllCheck = !isAllCheck;   
}
</script>

Answer 3

function uncheckElements()
{
 var uncheck=document.getElementsByTagName('input');
 for(var i=0;i<uncheck.length;i++)
 {
  if(uncheck[i].type=='checkbox')
  {
   uncheck[i].checked=false;
  }
 }
}

Answer 4

You can do this with jQuery very easy and more understandable :)

$('#mybutton').click(function(e) {
    $('.myCheckboxes').each(function(i,item){
        $(item).attr('checked', !$(item).is(':checked'));
    });
});

Try on jsFiddle

Answer 5

The problem boils down to how you're setting the checked property of the checkox. You're assigning a string with "true" where you should be assigning the boolean value true.

So to fix your code is easy:

if( isAllCheck == false ){
    cbarray[i].checked = true;
}else{ 
    cbarray[i].checked = false;
}

or, more succinctly

cbarray[i].checked = !isAllCheck

Live example: http://jsfiddle.net/SEJZP/

Answer 6

After validating that isAllCheck is correct with your UI logic, you may do both with a simple vanilla-js one-liner

Array.from(document.querySelectorAll('input[type=checkbox]').forEach(el => el.checked = isAllCheck);