[p5.js 2.0+ Bug Report]: assigning MediaElement.src leaves stale <source> children, so reading src returns the old source

[rajanpanth]

Most appropriate sub-area of p5.js?

DOM

p5.js version

2.x main (4b096e2)

Actual vs expected behavior

The src setter on p5.MediaElement removes existing <source> children with a forward index loop over the live HTMLCollection, which skips every other child as the collection reindexes:

const v = createVideo(['a.mp4', 'b.webm']);
v.src = 'c.mp4';
v.elt.childElementCount; // actual 2 (leftover b.webm + c.mp4), expected 1
v.src;                   // actual ends with 'b.webm' (getter returns children[0].src), expected 'c.mp4'

So after assigning a new source, reading v.src reports the old one, and the media element still lists the stale source first. The same code exists in 1.x, so this is longstanding rather than a 2.x regression.

Steps to reproduce

Outputs above are from executed runs against current main via the DOM unit test harness (the two new tests fail on unfixed code with expected 2 to deeply equal 1 and expected false to be true).

Note

I have a fix ready (iterate the live collection backwards, with a comment) plus 2 regression tests in the createVideo suite; the DOM suite passes 14 with it. Filing for approval per the contributing guide; will open the PR once approved.

[Dhirenderchoudhary]

@ksen0 i would like to work on this