Limitations

Keeping server work in #[Server] methods

Queries, services, Auth, Cache, files, mail and the clock (now(), date()) all belong to the server. If a browser method uses them, the build fails and tells you the file and line.

// A browser method: the build fails, because the clock belongs to the server.
public function stamp(): void
{
    $this->savedAt = now()->toTimeString();
}

// A #[Server] method runs on the server, where now() is available.
#[Server]
public function stamp(): void
{
    $this->savedAt = now()->toTimeString();
}

Creating components with mount()

Only the server can create a component that has a mount() method. It does so on the first request, on a visit, or during a #[Server] call of the component whose view places it. A change made only in the browser, such as $set or a browser method, can't place a new one. So a <nitro:dynamic-component> that switches to such a component needs one of those first.

Numbers, strings and patterns

• Numbers follow JavaScript. Integers are exact up to 2⁵³, so PHP_INT_MAX is 2⁵³-1 in the browser. A whole float arrives as an int. Functions such as tanh may differ in the last digit, just as they do between PHP builds.
• Strings are UTF-8. Byte functions such as strlen and substr count bytes, as PHP does. A result that isn't valid UTF-8 appears as U+FFFD.
• Regular expressions follow PCRE, translated to JavaScript. Features without an exact equivalent fail with a message: recursion, conditional groups, \K, backtracking verbs, callouts, (?|, inline modifiers inside the pattern, and duplicate group names. Without the /u flag, patterns match bytes.
• Unicode follows the browser. Case mapping and character classes use the browser's Unicode version, which can be older than PHP's.

What isn't available in the browser

• The $count argument of preg_replace(), and the percentage of similar_text()
• strip_tags() with allowed tags
• mb_convert_case() modes other than upper, lower and title
• Str:: methods that haven't been ported (such as plural, uuid and of), and Str::slug and Str::ascii in languages other than en
• htmlentities() and html_entity_decode() with ENT_HTML5, ENT_XHTML or ENT_XML1

Using one of these fails the build or fails with a message. They never give a different result from PHP. Call them from a #[Server] method instead.

Teleporting to portals

@teleport targets a named @portal instead of a CSS selector, so the server can render it too. You can define each @portal only once per page.

Next steps