How do I handle menus that include elements out of viewport?

I have a menu of ul and li elements.
The menu is built using javascript and document.createElement.

Multiple levels of sub menus (li -> ul) may exist.
If root li is above 3/4 of window.innerHeight, sub ul's top = 0 (bDropUp = false).
Otherwise sub ul's bottom = 0 (bDropUp = true) so it drops up, not down.

If not bDropUp the browser will extend the page as needed so I think that's acceptable.

BUT if bDropUp and part of the menu is above the viewport top that part of the menu becomes inaccessible.

How should I handle menus like this?

 

Did you ask Grok? I fixed a few things over the past couple of months simply asking what I wanted to get fixed and pasting the code.

https://x.com/i/grok

 

quikad: Thanks for the response.
It looks like an AD.
OK I'll bite. WHAT is grok and how much does it cost?

I did ask chatgpt and we went around in circles for about an hour to no avail.

I did realize though that within the PAGE it scrolls up and down just fine.
The problem is that the li element is above the PAGE so it's top is < 0.
I need to rectify that.

 

It's not an ad. Just log into your X account and start using it. It gives you 12 tries (which is a lot) then you have to wait 2 hours and you can get another 12 tries. I can't promise you that it will solve your issue, but it has the capacity to solve virtually any super complex problem.

PS Picture 1,000,000 deathshadows combined - that's grok when it comes to coding.

 

OK I tried to sign up. It wants me to play a 'match the icons' game all day.
I don't know what grok is but I'm NOT signing up for anything that's going to take that much of my time up for no good reason.
I have NO interest in anything on x.com

 

Fair enough. I myself use x for news, mostly. Post your code here with what exactly you want to get fixed, I'm going to post it to grok to see what it can do and I'll repost it here.

 

OK I'll bite again.
The problem is that I've got a menu li -> ul that is dropup.
Some of the li elements end up above the page top.
When I try to find out where the li is I use getBoundingClientRect().top.
The window's scrollY is 0 so there is no scroll.

getBoundingClientRect returns over 400 (negative).
I add padding to the top of the body so I can see the li.
The li is actually about 150 pixels above the page.

Why is getBoundingClientRect coming up with such a high number and how can I find out how many pixels above the page the li is actually positioned.

 

Here's the FULL answer:

The issue you're describing arises because getBoundingClientRect().top returns the position of an element relative to the viewport, not the top of the document or the page's content area. When an element is positioned above the viewport (e.g., in a dropup menu where some <li> elements are above the visible area), getBoundingClientRect().top will return a negative value indicating how far above the viewport's top edge the element is. However, the large negative value you're seeing (e.g., -400) may be influenced by several factors, such as CSS positioning, transforms, or other layout properties affecting the element or its ancestors.
Here’s why this is happening and how you can accurately determine how many pixels the <li> is above the page:
Why getBoundingClientRect().top Returns a Large Negative Value
Viewport-Relative Positioning:
getBoundingClientRect().top measures the distance from the top of the element to the top of the viewport. If the <li> is positioned above the viewport, the value will be negative.
For example, if the <li> is 150 pixels above the viewport's top edge, getBoundingClientRect().top will return approximately -150. A value like -400 suggests the element is positioned even further above the viewport.
CSS Positioning or Transforms:
If the <li> or its parent <ul> is using position: absolute, position: fixed, or CSS transforms (e.g., transform: translateY(...)), the element's position may be offset in ways that affect getBoundingClientRect().top.
For instance, if the <ul> is positioned with a negative top value or a transform, this can push the <li> elements further above the viewport, resulting in a larger negative value.
Parent Element Context:
The <ul> or its container might have a positioning context (e.g., position: relative, absolute, or fixed) that shifts the coordinate system. This can cause the <li> to appear further above the viewport than expected.
Body or Container Styling:
If the <body> or a parent container has margins, padding, or other styles (e.g., margin-top, transform, or position), these can affect the positioning calculations, leading to unexpected getBoundingClientRect().top values.
For example, if you added padding to the <body> to make the <li> visible, this might shift the viewport's reference point, but it doesn't directly affect getBoundingClientRect().top unless other styles are at play.
No Scroll (scrollY = 0):
Since window.scrollY is 0, the viewport is at the top of the document. This means getBoundingClientRect().top directly reflects the element's position relative to the top of the visible window. A value of -400 indicates the element is 400 pixels above the viewport's top edge.
Why the <li> Appears 150 Pixels Above the Page
The discrepancy between the -400 from getBoundingClientRect().top and the visual estimate of "150 pixels above the page" could be due to:
Visual Misestimation: The actual distance above the viewport might be larger than it appears visually, especially if the element is styled with transforms, scaling, or other effects.
Parent Positioning: The <ul> or its container might be offset by a large amount (e.g., top: -250px or a transform), causing the <li> to be positioned further up than expected.
Browser or Viewport Quirks: Some browsers may include additional offsets (e.g., browser UI elements like the address bar) in the coordinate calculations, though this is less likely.
How to Find the Actual Pixels Above the Page
To accurately determine how many pixels the <li> is above the top of the document (not just the viewport), you need to account for the document's coordinate system and any offsets introduced by scrolling or parent elements. Here’s how you can do it:
Step 1: Calculate the Document-Relative Position
Use getBoundingClientRect().top combined with window.scrollY to get the element’s position relative to the top of the document:

javascript

const li = document.querySelector('li'); // Select your <li> element
const rect = li.getBoundingClientRect();
const distanceAboveViewport = rect.top; // Negative if above the viewport
const distanceFromDocumentTop = rect.top + window.scrollY; // Absolute position relative to document top
console.log('Distance above viewport:', distanceAboveViewport);
console.log('Distance from document top:', distanceFromDocumentTop);

Since window.scrollY is 0 in your case, distanceFromDocumentTop will equal rect.top (e.g., -400). This confirms the element is 400 pixels above the document's top edge.
Step 2: Determine Pixels Above the Page
If the <li> is above the document’s top edge (i.e., distanceFromDocumentTop is negative), the number of pixels above the page is simply the absolute value of distanceFromDocumentTop:
javascript

const pixelsAbovePage = Math.abs(distanceFromDocumentTop);
console.log('Pixels above the page:', pixelsAbovePage); // e.g., 400

This gives you the exact number of pixels the <li> is positioned above the document’s top edge.
Step 3: Account for Parent Offsets
If the <li> is inside a positioned parent (e.g., a <ul> with position: absolute or relative), you may need to check the parent’s position to understand why the <li> is so far above the viewport. Use getBoundingClientRect() on the parent <ul>:
javascript

const ul = document.querySelector('ul');
const ulRect = ul.getBoundingClientRect();
console.log('Parent <ul> top:', ulRect.top);

If ulRect.top is also negative, the <ul> itself is positioned above the viewport, contributing to the large negative value for the <li>.
Step 4: Debugging the Discrepancy
If pixelsAbovePage (e.g., 400) doesn’t match your visual estimate (e.g., 150 pixels), inspect the following:
CSS Styles: Check for position, top, transform, or margin on the <li>, <ul>, or their ancestors. For example:
css

ul {
position: absolute;
top: -200px; /* This could push the <ul> and its <li> children upward */
}

Transforms: A transform: translateY(-100px) on the <ul> or <li> can shift the element without affecting offsetTop directly but will impact getBoundingClientRect().top.
Body Padding: The padding you added to the <body> might make the <li> appear closer to the viewport visually, but it doesn’t change getBoundingClientRect().top unless it alters the layout of the <ul> or <li>.
Use the browser’s DevTools (right-click the <li> and select “Inspect”) to check computed styles and the element’s layout.
Step 5: Alternative Method Using offsetTop
If you want to measure the position relative to the document without relying on getBoundingClientRect, you can use the offsetTop property, which gives the distance from the element’s top to its offsetParent’s top. However, you’ll need to walk up the DOM to account for all parent offsets:
javascript

function getOffsetFromDocumentTop(element) {
let offsetTop = 0;
let currentElement = element;
while (currentElement) {
offsetTop += currentElement.offsetTop;
currentElement = currentElement.offsetParent;
}
return offsetTop;
}
const li = document.querySelector('li');
const offsetFromTop = getOffsetFromDocumentTop(li);
const pixelsAbovePage = offsetFromTop < 0 ? Math.abs(offsetFromTop) : 0;
console.log('Offset from document top:', offsetFromTop);
console.log('Pixels above the page:', pixelsAbovePage);

This method accounts for nested offsetParent elements but may still be affected by transforms or non-standard positioning.
Fixing the Visual Discrepancy
If you want the <li> to appear closer to the top of the page (e.g., only 150 pixels above instead of 400), you can adjust the positioning of the <ul> or <li>:
Adjust the <ul> Position:
If the <ul> is positioned with position: absolute or fixed, reduce the negative top or transform value:
css

ul.dropup {
position: absolute;
top: -150px; /* Adjust to desired distance */
}

Dynamically Adjust Based on Position:
If the dropup menu’s position is dynamic, use JavaScript to ensure no <li> is too far above the viewport:
javascript

const ul = document.querySelector('ul');
const rect = ul.getBoundingClientRect();
if (rect.top < -150) {
ul.style.top = `${parseInt(ul.style.top) + (rect.top + 150)}px`; // Adjust to keep within 150px
}

Add a Scrollable Container:
If the menu is too tall, consider making the <ul> scrollable so users can access items above the viewport:
css

ul.dropup {
max-height: 300px;
overflow-y: auto;
}

Summary
Why the large negative value? getBoundingClientRect().top returns a negative value (e.g., -400) because the <li> is 400 pixels above the viewport’s top edge, likely due to the <ul>’s positioning or transforms.
How to find pixels above the page? Use Math.abs(element.getBoundingClientRect().top + window.scrollY) to calculate the distance above the document’s top edge.
Fixing the discrepancy: Inspect CSS styles (position, top, transform) on the <li> and <ul>, and adjust positioning to reduce the distance above the viewport if needed.
Debugging: Use DevTools to check computed styles and verify parent offsets. Alternatively, use offsetTop with a recursive function to calculate the document-relative position.
If you share the relevant HTML/CSS or a description of the <ul> and <li> styling, I can provide a more tailored solution!

 

It tells me pretty much what chatgpt told me.
If you copied and pasted it, it was a pretty good bit more verbose.

This: Math.abs(element.getBoundingClientRect().top + window.scrollY)
and This: Math.abs(element.getBoundingClientRect().top)
return the same thing.

I add padding to the body AFTER I call getBoundingClientRect().top so that's not the issue:
Here's the code:

      const rct = elLi.getBoundingClientRect();
      if(rct.top < 0) {           
            nPadding = Math.abs(rct.top + window.scrollY).toFixed(2);
            document.body.style.paddingTop = nPadding + "px";
            window.scrollTo({ top: 0, behavior: 'smooth' });
        }

Code (markup):

The actual problem is that the added padding puts the top of the page WAY above the li.
That's proof that getBoundingClientRect isn't working right. It's returning the wrong number.
It does render the top of the menu accessible but it's got too much padding (by about 300 pixels).
That's javascript.




Thanks for the help.