javascript – How to remove browser scroll when opening a menu, and turn it back on after closing it?

Question:

How to remove the browser scroll when opening a menu, and after closing it, turn it back on? Found this solution, but I don't know how to turn it off after the menu closes:

document.onmousewheel = document.onwheel = function () {
  return false;
};
document.addEventListener("MozMousePixelScroll", function () {
  return false
}, false);
document.onkeydown = function (e) {
  if (e.keyCode >= 33 && e.keyCode <= 40) return false;
};
return false;

Here is the link to the codepen

PS overflow: hidden; does not fit, because after canceling this property, it will scroll to the very top of the page.

Answer:

Take out the definition you need to scroll or not into an external variable and return it in your functions:

 window.can_scroll = true;

 document.onmousewheel = document.onwheel = function () {
    return window.can_scroll;
 };
 document.addEventListener("MozMousePixelScroll", function () {
    return window.can_scroll
 }, false);
 document.onkeydown = function (e) {
    if (e.keyCode >= 33 && e.keyCode <= 40) return window.can_scroll;
 };

Or remove listeners:

 // выключить скролл
 document.onmousewheel = document.onwheel = function () {
    return false;
 }; 
 function scrollOrNot() {
     return false;
 }
 document.addEventListener("MozMousePixelScroll", scrollOrNot, false);
 document.onkeydown = function (e) {
    if (e.keyCode >= 33 && e.keyCode <= 40) return window.can_scroll;
 };

 // включить скролл
 document.onmousewheel = document.onwheel = function () {
    return true;
 }; 
 document.onkeydown = function (e) {
    return true;
 };
 document.removeEventListener("MozMousePixelScroll", scrollOrNot, false);