NgbTypeahead component doesn't scroll inside a scrollable component

Question

I am using NgbTypeahead component of ng-bootstrap. My problem is, when I put the typeahead component inside a scrollable component and make a scroll down, the position of dropdown container doesn't change.

<div style="height: 300px;   overflow-y: auto;">
...
<input id="typeahead-template" type="text" class="form-control [(ngModel)]="model" 
       [ngbTypeahead]="search" [resultTemplate]="rt [inputFormatter]="formatter" />
...
</div>

It could be a small CSS issue but I could not find the solution.

Here is the plunkr : http://plnkr.co/edit/rxOhDy72YWlLy9U4Ujcd?p=preview

Type in a character in the text box and then scroll up-down

Answer 1

As NgbTypeahead does not have support with scroll, we need to handle from component. Use showDropdownEle function on keydown of Input.

private isElementInViewport(el, inputElem) {
const rect = el.getBoundingClientRect();
const rectElem = inputElem.getBoundingClientRect();
console.log(rectElem);
return (
  rect.top >= rectElem.bottom &&
  rect.left >= 0 &&
  rect.bottom <= (rectElem.bottom + rect.offsetHeight) &&
  rect.right <= (window.innerWidth || document.documentElement.clientWidth)
  );
}

public showDropdownEle(event) {
if (event.keyCode === 38 || event.keyCode === 40) {
  if (event.target.nextElementSibling && event.target.nextElementSibling.nodeName === 'NGB-TYPEAHEAD-WINDOW') {
    let activeDropdownEle = (event.keyCode === 40) ? event.target.nextElementSibling.querySelector('.active').nextElementSibling : event.target.nextElementSibling.querySelector('.active').previousElementSibling;
    if (!activeDropdownEle) {
      const allDropdownElems = event.target.nextElementSibling.querySelectorAll('.dropdown-item');
      activeDropdownEle = (event.keyCode === 38) ? allDropdownElems[allDropdownElems.length - 1] : allDropdownElems[0];
    }
    if (!this.isElementInViewport(activeDropdownEle, event.target) && event.keyCode === 40) {
      activeDropdownEle.scrollIntoView(false);
    }
    if (!this.isElementInViewport(activeDropdownEle, event.target) && event.keyCode === 38) {
      activeDropdownEle.scrollIntoView(true);
    }
  }
}
}