Re: [csswg-drafts] Do the CSSOM part of #866 (#3109)

```js
style.shorthand = 'a'
```

See #7195 for this case

```js
style.shorthand = 'var(--custom)'
style.longhand;  // 'var(--custom)'
```

No, because we could have `--custom: b`, then `longhand` will compute to `c`, and `var(--custom)` is a bad serialization since `longhand: b` is invalid.

```js
style.longhand = 'var(--custom)'
style.shorthand; // 'var(--custom)'
```

Similarly, if `--custom: c`, then the shorthand will "compute" to `shorthand: b`, so `var(--custom)` is a bad serialization.

See https://drafts.csswg.org/css-variables-1/#variables-in-shorthands

> if any of the component [longhand properties](https://drafts.csswg.org/css-cascade-5/#longhand) for a given [shorthand](https://drafts.csswg.org/css-cascade-5/#shorthand-property) are [pending-substitution values](https://drafts.csswg.org/css-variables-1/#pending-substitution-value), or contain [var()](https://drafts.csswg.org/css-variables-1/#funcdef-var) functions of their own that have not yet been substituted, the shorthand property must serialize to the empty string.

-- 
GitHub Notification of comment by Loirooriol
Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/3109#issuecomment-1307506131 using your GitHub account


-- 
Sent via github-notify-ml as configured in https://github.com/w3c/github-notify-ml-config

Received on Tuesday, 8 November 2022 16:39:40 UTC