Bug 245941 – IntersectionObserver Api Ratio Less Than 1 While Toolbar Visible

• Status: NEW
• Component: Layout and Rendering

[Mahdi]

Created attachment 462761 [details]
Image of example on Safari 16 - iPhone14 - iOS 16

Problem:

IntersectionObserver api in every desktop browser and mobile browsers that does not have `Toolbar` like safari on bottom of the webpage, is giving the intersectionRatio of `1` when the observed target reached the top of view:

------------------- <-- top of browser web view
+++++++++++++++++++ <-- ELEMENT THAT REACHES THE TOP
|   Hello World   |
|                 |
+++++++++++++++++++


------------------- <-- bottom of browser web view

But in Safari on iOS with Toolbar that in the browser view, it gives the value of ~0.9 for intersectionRatio which is INCORRECT!?

[Mahdi]

Link to repo:
https://github.com/mahdi-farnia/webkit-intersection-observer-bug

[Radar WebKit Bug Importer]

<rdar://problem/100728324>

[Ahmad Saleem]

Changed test to following JSFiddle: https://jsfiddle.net/58h0ko2w/

In Chrome Canary 118, I get following in JSFiddle Console:

"Ratio is: ", 1
"%cWorking", "color: green;"

_____

In WebKit ToT (266852@main):

"Ratio is: ", 0.9980040192604065

and get console error: <a class='gotoLine' href='#"Expect ratio to be 1 but got 0.9980040192604065"'>"Expect ratio to be 1 but got 0.9980040192604065"</a>

____

In Firefox Nightly 118:

Same as Firefox but different ratio but also error.