function checkAllOnV30() {
    const ischecked = checkAllOn30.checked;
    let btnText = document.querySelector(".selection30.On");

    
    for (let i = 0;i < villesOn30.length; i++) {
        villesOn30[i].checked = ischecked;
    }

        if(ischecked && villesOn30.length > 0) {
            btnText.innerText = `( ${villesOn30.length} )`;
            for (let i = 0;i < villesOn30.length; i++) {
                villesOn30[i] = villesOn30[i].classList.add("checked30");
                listArray = listArray.filter(e => e !== villesOn30[i].value);
                listArray.push(villesOn30[i].value);
            }   
            btn.innerHTML = listArray.join(", ");
            Vsouh.value = btn.innerHTML;
        }
        else {
            btnText.innerText = "";
            for (let i = 0;i < villesOn30.length; i++) {
                listArray = listArray.filter(e => e !== villesOn30[i].value);
                villesOn30[i] = villesOn30[i].classList.remove("checked30");
            }
            btn.innerHTML = listArray.join(", ");
            Vsouh.value = btn.innerHTML;
    }
};