Custom dropdown not taking 'change' event-CodePudding

I have created a custom dropdown with W3c example https://www.w3schools.com/howto/howto_custom_select.asp

Its working fine but the problem is its not working with change event, See the example below, Open console panel, when you change the option with actual dropdown it will show "CHANGE" but when you change with custom dropdown it doesnt trigger the change event.

https://codepen.io/danishadeel/pen/XWVddpW

var x, i, j, l, ll, selElmnt, a, b, c;
/* Look for any elements with the class "custom-select": */
x = document.getElementsByClassName("custom-select");
l = x.length;
for (i = 0; i < l; i  ) {
  selElmnt = x[i].getElementsByTagName("select")[0];
  ll = selElmnt.length;
  /* For each element, create a new DIV that will act as the selected item: */
  a = document.createElement("DIV");
  a.setAttribute("class", "select-selected");
  a.innerHTML = selElmnt.options[selElmnt.selectedIndex].innerHTML;
  x[i].appendChild(a);
  /* For each element, create a new DIV that will contain the option list: */
  b = document.createElement("DIV");
  b.setAttribute("class", "select-items select-hide");
  for (j = 1; j < ll; j  ) {
    /* For each option in the original select element,
    create a new DIV that will act as an option item: */
    c = document.createElement("DIV");
    c.innerHTML = selElmnt.options[j].innerHTML;
    c.addEventListener("click", function(e) {
        /* When an item is clicked, update the original select box,
        and the selected item: */
        var y, i, k, s, h, sl, yl;
        s = this.parentNode.parentNode.getElementsByTagName("select")[0];
        sl = s.length;
        h = this.parentNode.previousSibling;
        for (i = 0; i < sl; i  ) {
          if (s.options[i].innerHTML == this.innerHTML) {
            s.selectedIndex = i;
            h.innerHTML = this.innerHTML;
            y = this.parentNode.getElementsByClassName("same-as-selected");
            yl = y.length;
            for (k = 0; k < yl; k  ) {
              y[k].removeAttribute("class");
            }
            this.setAttribute("class", "same-as-selected");
            break;
          }
        }
        h.click();
    });
    b.appendChild(c);
  }
  x[i].appendChild(b);
  a.addEventListener("click", function(e) {
    /* When the select box is clicked, close any other select boxes,
    and open/close the current select box: */
    e.stopPropagation();
    closeAllSelect(this);
    this.nextSibling.classList.toggle("select-hide");
    this.classList.toggle("select-arrow-active");
  });
}

function closeAllSelect(elmnt) {
  /* A function that will close all select boxes in the document,
  except the current select box: */
  var x, y, i, xl, yl, arrNo = [];
  x = document.getElementsByClassName("select-items");
  y = document.getElementsByClassName("select-selected");
  xl = x.length;
  yl = y.length;
  for (i = 0; i < yl; i  ) {
    if (elmnt == y[i]) {
      arrNo.push(i)
    } else {
      y[i].classList.remove("select-arrow-active");
    }
  }
  for (i = 0; i < xl; i  ) {
    if (arrNo.indexOf(i)) {
      x[i].classList.add("select-hide");
    }
  }
}

/* If the user clicks anywhere outside the select box,
then close all select boxes: */
document.addEventListener("click", closeAllSelect);

$('.custom-select select').on('change', function(){
  console.log('CHANGE')
})

CodePudding user response：

Events are only fired automatically when triggered by user action. Because you are programatically changing the selected item, no event is emitted.

You can manually dispatch the event with

s.dispatchEvent(new Event('change'));

Here is a good resource on dispatching and listening to events

https://developer.mozilla.org/en-US/docs/Web/Events/Creating_and_triggering_events