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A BBC navigation bar component broke depending on the external monitor

(www.joshtumath.uk)
294 points ulrischa | 3 comments | 18 Nov 24 15:28 UTC | HN request time: 0.406s | source
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account42 ◴[18 Nov 24 16:38 UTC] No.42174070[source]▶
Why are websites getting mouse position in screen coordinates in the first place?
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1. DCH3416 ◴[18 Nov 24 16:48 UTC] No.42174200[source]▶
Uh. So they can keep track of what the user is doing?

Why would you just send a document when you can generate a heat map of where the user is on your website. And then complain about the performance and wonder why it costs so much to run a modern website.

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2. ◴[18 Nov 24 16:56 UTC] No.42174285[source]▶
3. Sayrus ◴[18 Nov 24 16:58 UTC] No.42174308[source]▶
The issue isn't so much the coordinate of the mouse within a page, but that the coordinates are relative to the virtual screen layout. It describes where your window is located on the screen(s) and the click is expressed in screen coordinates. Mapping those coordinates to your website's renderer coordinates requires additional calculation.

layerX[1] while non-standard is supported and returns a position relative to the top of the page or the top of the parent element. This makes coordinates positive only and 50,50 is the same for all users. For screenX, 3000,1567 is the same coordinate as 15,37 depending on where the window is located.

[1] https://developer.mozilla.org/en-US/docs/Web/API/MouseEvent/...