CODEWITHSUNDEEP
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Jeanluca Scaljeri
Jeanluca Scaljeri

Reputation: 29139

Find first scrollable parent

I have this situation in which I need to scroll an element into the viewport. The problem is that I don't know which element is scrollable. For example, in Portrait the body is scrollable and in Landscape its an other element (and there are more situation which change the scrollable element)

Now the question, given an element which needs to be scrolled into the viewport, what is the best way to find its first scrollable parent ?

I've setup a demo here. With the button you can toggle between two different situations

<div class="outer">
    <div class="inner">
        <div class="content"> 
            ...
            <span>Scroll me into view</span>
        </div>
    </div>
</div>

The body is scrollable or .outer

Any suggestions ?

Upvotes: 105

Views: 77543

Answers (10)

dgropp
dgropp

Reputation: 35

const scrollStyles = ['scroll', 'auto'];

function findScrollParent(element: HTMLElement | null): HTMLElement | Window {
  const parent = element?.parentElement;
  // if parent is null there is no scroll element, so return window
  if (!parent) return window;
  // can be modified to include also overflowX
  const { overflowY } = getComputedStyle(parent);
  // if parent has either overflowY scroll or auto return parent
  if (scrollStyles.includes(overflowY)) return parent;
  // otherwise continue search
  return findScrollParent(parent);
}

Upvotes: 0

Gabriel Jablonski
Gabriel Jablonski

Reputation: 943

A more efficient version of @ncubica's answer.

In this version, we check each parent one by one, and stop at the first one which is scrollable. Also, getComputedStyle() only gets called once per parent.

const isScrollable = (node: Element) => {
  if (!(node instanceof HTMLElement || node instanceof SVGElement)) {
    return false
  }
  const style = getComputedStyle(node)
  return ['overflow', 'overflow-x', 'overflow-y'].some((propertyName) => {
    const value = style.getPropertyValue(propertyName)
    return value === 'auto' || value === 'scroll'
  })
}

export const getScrollParent = (node: Element): Element => {
  let currentParent = node.parentElement
  while (currentParent) {
    if (isScrollable(currentParent)) {
      return currentParent
    }
    currentParent = currentParent.parentElement
  }
  return document.scrollingElement || document.documentElement
}

Upvotes: 6

Stefano Nardo
Stefano Nardo

Reputation: 1647

Just check if the scrollbar is visible, if not look to the parent.

function getScrollParent(node) {
  if (node == null) {
    return null;
  }

  if (node.scrollHeight > node.clientHeight) {
    return node;
  } else {
    return getScrollParent(node.parentNode);
  }
}

Upvotes: 99

jimmont
jimmont

Reputation: 2544

this is what I have so-far that seems to work across web component custom element shadowRoots; we might expand it further to add a scroll event handler once scrolling starts to unload this handling and track a specific node's scroll event

function scroller(node){ return node.scrollTop }
function handler(event){
        const path = event.composedPath();
        const scrollNode = path.find(scroller);
        const scrollNodes = path.filter(scroller);
        console.warn('scroll!',{scrollNode, scrollNodes});
}
window.addEventListener('mousewheel', handler, {capture: true});
window.addEventListener('keydown', handler, {capture: true});

Upvotes: 1

ncubica
ncubica

Reputation: 8485

the answer with most votes doesn't work in all cases scrollHeight > clientHeight can be true even if there is no scrollbar.

I found this gist solution https://github.com/olahol/scrollparent.js/blob/master/scrollparent.js#L13

^ total credit to https://github.com/olahol who wrote the code.

Refactored it to es6:

export const getScrollParent = (node) => {
  const regex = /(auto|scroll)/;
  const parents = (_node, ps) => {
    if (_node.parentNode === null) { return ps; }
    return parents(_node.parentNode, ps.concat([_node]));
  };

  const style = (_node, prop) => getComputedStyle(_node, null).getPropertyValue(prop);
  const overflow = _node => style(_node, 'overflow') + style(_node, 'overflow-y') + style(_node, 'overflow-x');
  const scroll = _node => regex.test(overflow(_node));

  /* eslint-disable consistent-return */
  const scrollParent = (_node) => {
    if (!(_node instanceof HTMLElement || _node instanceof SVGElement)) {
      return;
    }

    const ps = parents(_node.parentNode, []);

    for (let i = 0; i < ps.length; i += 1) {
      if (scroll(ps[i])) {
        return ps[i];
      }
    }

    return document.scrollingElement || document.documentElement;
  };

  return scrollParent(node);
  /* eslint-enable consistent-return */
};

you can use it like:

const $yourElement = document.querySelector('.your-class-or-selector');
getScrollParent($yourElement);

Upvotes: 14

Drew2
Drew2

Reputation: 401

Using google chrome dev tools, when you've scrolled partially down the page, inspect the page, select the DOM node that you think might be the one that is being scrolled. Then pull up the console (hit ESC from within the Elements tab of the dev tools) and type $0.scrollTop. This will print out the current scroll position of that element. If it is NOT 0 then you will know that that is the element that is being scrolled.

Upvotes: 4

Mohd Abdul Mujib
Mohd Abdul Mujib

Reputation: 13938

Building upon further on the @Web_Designer's answer,

If you are passing the jQuery object for that element and are getting the following error,

Failed to execute 'getComputedStyle' on 'Window': parameter 1 is not of type 'Element'

Then try passing just the Dom Node element which btw resides at array key 0 if the element is a single element. Eg. 

getScrollParent(jQuery("#" + formid)[0])

Upvotes: 1

Web_Designer
Web_Designer

Reputation: 74560

This is a pure JS port of the jQuery UI scrollParent method that cweston spoke of. I went with this rather than the accepted answer's solution which will not find the scroll parent if there's no content overflow yet.

The one difference with my port is that, if no parent is found with the right value for the CSS overflow property, I return the <body> element. JQuery UI, instead returned the document object. This is odd as values like .scrollTop can be retrieved from the <body> but not the document.

function getScrollParent(element, includeHidden) {
    var style = getComputedStyle(element);
    var excludeStaticParent = style.position === "absolute";
    var overflowRegex = includeHidden ? /(auto|scroll|hidden)/ : /(auto|scroll)/;

    if (style.position === "fixed") return document.body;
    for (var parent = element; (parent = parent.parentElement);) {
        style = getComputedStyle(parent);
        if (excludeStaticParent && style.position === "static") {
            continue;
        }
        if (overflowRegex.test(style.overflow + style.overflowY + style.overflowX)) return parent;
    }

    return document.body;
}

Upvotes: 64

cweston
cweston

Reputation: 11647

If you are using jQuery UI you can use the scrollParent method. Have a look at the API or the source.

From the API:

.scrollParent(): Get the closest ancestor element that is scrollable

This method does not accept any arguments. This method finds the nearest ancestor that allows scrolling. In other words, the .scrollParent() method finds the element that the currently selected element will scroll within.

Note: This method only works on jQuery objects containing one element.

If you are not using jQuery UI but are using jQuery, then there are alternative independent libraries providing similar functionality, such as:

jquery-scrollparent

Upvotes: 9

NiZa
NiZa

Reputation: 3926

I think you want this.

$('button').click(function() {
  $("body").addClass("body");
  $('.outer').toggleClass('scroller');
  check($(".content"));
});

function check(el) {
  var overflowY = el.css("overflow-y");  
  if (overflowY == "scroll") {
    alert(el.attr("class") + " has");
  } else {
    if(el.parent().length > 0)
   	  check(el.parent());
    else 
      return false;
  }
}
body {
  height: 450px;
  overflow-y: scroll;
}

div.inner {
  width: 200px;
  height: 400px;
  border: 1px solid #000;
}

div.outer {
  width: 200px;
  height: 200px;
}

div.outer.scroller {
  overflow-y: scroll;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<button>
  toggle
</button>
<div class="outer">
  <div class="inner">
    <div class="content">
      "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor
      in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum." adipiscing elit, sed do eiusmod tempor incididunt ut
      labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur
      sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
    </div>
  </div>
</div>

Upvotes: 1

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