First Paragraph Has an issue

I would consider revising the first paragraph.

Mainly this part:

Isn’t it a bit strange? Why does the handler on <div> run if the actual click was on <em>?

It comes across as infantilizing and momentarily derailed my reading on a topic I was actually wanting to read about. It works well if your target audience is four to six year-olds.

Simply saying something like "this is because they are nested" or similar would do the trick.

I will concede that I am likely not the target audience. I saw the term bubbling, was unfamiliar with it, googled, saw right away from this article that it was talking about propagating events. I will still finish reading the article, since JavaScript is not my forte, but that line was a bit unexpected in an article at this level.

I will also note that the comments, overall, look to be positive, so the article is well received.

引用された最初の段落を含むチュートリアル記事を特定し、event bubblingについて周囲で説明されている内容を読みます。疑問視されている表現を使わず、ネストされた要素を直接説明するように段落を修正し、その後、記事が正確で読みやすいままであることを確認します。