Unclear content for the Intersection Observer API

[haocheng6]

MDN URL

https://developer.mozilla.org/en-US/docs/Web/API/Intersection_Observer_API

What specific section or headline is this issue about?

Intersection change callbacks

What information was incorrect, unhelpful, or incomplete?

The page says

Each entry in the list of thresholds is an IntersectionObserverEntry object describing one threshold that was crossed; that is, each entry describes how much of a given element is intersecting with the root element, whether or not the element is considered to be intersecting or not, etc.

But I don't understand how each entry in the list of thresholds is an object. Each entry in the list of thresholds should be just a threshold which is a number. The sentence seems incomplete to me.

What did you expect to see?

I expect to see the quoted sentence above is corrected to avoid confusion.

Do you have any supporting links, references, or citations?

No response

Do you have anything more you want to share?

No response

MDN metadata

Page report details

• Folder: en-us/web/api/intersection_observer_api
• MDN URL: https://developer.mozilla.org/en-US/docs/Web/API/Intersection_Observer_API
• GitHub URL: https://github.com/mdn/content/blob/main/files/en-us/web/api/intersection_observer_api/index.md
• Last commit: 5b20f5f
• Document last modified: 2024-12-19T15:37:45.000Z

[Josh-Cena]

Instead of these two paragraphs, which explains the same thing twice, the second time in an imprecise way:

The list of entries received by the callback includes one entry for each threshold-crossing event — multiple entries can be received at a time, either from multiple targets or from a single target crossing multiple thresholds in a short amount of time. The entries are dispatched using a queue, so they should be ordered by the time they were generated, but you should preferably use IntersectionObserverEntry.time to correctly order them.

Each entry in the list of thresholds is an IntersectionObserverEntry object describing one threshold that was crossed; that is, each entry describes how much of a given element is intersecting with the root element, whether or not the element is considered to be intersecting or not, etc. The entry only contains information about that particular instant — if you want information that requires tracking over time, such as the scroll direction and speed, you may need to compute that yourself by memorizing previously received entries.

We should merge them:

The list of entries received by the callback includes one IntersectionObserverEntry object for each threshold-crossing event — multiple entries can be received at a time, either from multiple targets or from a single target crossing multiple thresholds in a short amount of time. The entries are dispatched using a queue, so they should be ordered by the time they were generated, but you should preferably use IntersectionObserverEntry.time to correctly order them. Each entry describes how much of a given element is intersecting with the root element, whether or not the element is considered to be intersecting or not, etc. The entry only contains information about that particular instant — if you want information that requires tracking over time, such as the scroll direction and speed, you may need to compute that yourself by memorizing previously received entries.