Add/remove textbox value when checkbox change

Question

I have the following jquery code where i want to remove the value from the textfield if the checkbox is unchecked and add if it is checked.

initially all the values comes in the textbox as the ^ seperator. and all checkboxes checked

here is y piece of code:

$(document).on('change','._invoice',function() { 
    var mystr = $(this).attr('data-id').is(":checked");
    if(mystr) {
        var returnVal = confirm("Are you sure?");
        $(this).attr("checked", returnVal);
    }    
    });
});

Text field values and i also want to remove the separator and add the name at the last with ^ as separator.

Robert Berenson^Nancy Foster^Richard Gourhan^LORI HEDMAN^Pui Hoang^Linda Lee^Kristen McDonald^Matthew Miller^Tricia Roland^Terry West

Answer 1

var txt = document.getElementById( 'droptxt' ),
            content = document.getElementById( 'content' ),
            list = document.querySelectorAll( '.content input[type="checkbox"]' ),
            quantity = document.querySelectorAll( '.quantity' );
        txt.addEventListener( 'click', function() {
            content.classList.toggle( 'show' )
        } )

        window.onclick = function( e ) {
            if ( !e.target.matches( '.list' ) ) {
                if ( content.classList.contains( 'show' ) ) content.classList.remove( 'show' )
            }
        }

        list.forEach( function( item, index ) {
            item.addEventListener( 'click', function() {
                calc()
            } )
        } )

        function calc() {
            for ( var i = 0, arr = []; i < list.length; i++ ) {
            let spanArray = [];
            document.querySelectorAll('span').forEach(element => {
                spanArray.push(element.innerHTML);
            });
            
                if ( list[ i ].checked ) arr.push( list[ i ].value + " "+ spanArray)
            }   
            txt.value = arr.join(', ')
        }

h1 {
            color: #0000ff;
        }
        #droptxt {
            padding: 8px;
            width: 300px;
            cursor: pointer;
            box-sizing: border-box
        }
        .dropdown {
            position: relative;
            display: inline-block
        }
        .content {
            display: none;
            position: absolute;
            background-color: #f1f1f1;
            min-width: 200px;
            overflow: auto;
            box-shadow: 0 8px 16px 0 rgba(0, 0, 0, .2);
            z-index: 1
        }
        .content div {
            padding: 10px 15px
        }
        .content div:hover {
            background-color: #ddd
        }
        .show {
            display: block
        }

<h1>KIAAT</h1>
    <b>Adding/Removing Checkbox Values into TextArea</b>
    <br><br>
    <input type="text" id="droptxt" class="list" placeholder="Select the values" readonly>
        <div id="content" class="content">
            <div id="market" class="list">
            <label><input type="checkbox" id="market" class="list" value="apple" /> Apple</label>
            </div>
            
            <div class="list">
            <label><input type="checkbox" id="banana" class="list" value="Banana" /> Banana</label>
            </div>
            
            <div class="list">
            <label><input type="checkbox" id="pineapple" class="list" value="Pineapple" /> Pineapple</label>
            </div>
        </div>