Fix: join srcset in source with ", "

[Shinyaigeek]

↪️ Pull Request

Fixes: #7884

I found this is parcel’s issue. htmlnano depends on srcset, npm module to parse srcset attribute and after sindresorhus/srcset#11 PR was merged srcset module cannot parse srcset attribute without whitespace after “,” because hoge.png,bar.png is a valid URL.

However, parsel joins multiple image URLs in srcset attribute with “,” so this issue happens. parcel should join multiple image URLs in srcset attribute with “, “(with space), so I fixed so.

💻 Examples

<source srcset="hoge.png?as=webp&width=400, hoge.png?as=webp&width=800 2x">

into transformed into above by HTMLTransformer

<source srcset="hoge.HASH.png,hoge.HASH.png 2x">

but srcset module cannot parse this srcset attribute as a two image URLs.

🚨 Test instructions

I fixed html srcset integration testcase to check output HTML's srcset is valid.

✔️ PR Todo

• Added/updated unit tests for this change
• Filled out test instructions (In case there aren't any unit tests)
• Included links to related issues/PRs

[mischnic]

https://html.spec.whatwg.org/multipage/images.html#srcset-attribute:

If present, its value must consist of one or more image candidate strings, each separated from the next by a U+002C COMMA character (,). If an image candidate string contains no descriptors and no ASCII whitespace after the URL, the following image candidate string, if there is one, must begin with one or more ASCII whitespace.

[wbinnssmith]

might be worth a comment explaining the significance of the trailing space

[Shinyaigeek]

Sorry for late response, b19e0af 👍