Emoji Converter

Turn 🐘 into :elephant: and back, with a whole PHP interpreter compiled to WebAssembly, running in your browser. Because we could.

Try it online

Emoji Converter converts emoji to shortcodes (GitHub, GitLab, Slack, text), to their names in 136 languages, or to nothing at all, and back to emoji. The conversion is done by symfony/emoji, in PHP, in your browser: there is no server, your text never leaves the tab.

Is this a joke?

Mostly. symfony/emoji converts with a good old strtr(), and we ship 8 MB of WebAssembly to call it. But it works, it is fast (a few milliseconds per conversion, PHP boot included), and it was a good excuse to build PHP with the intl extension for the browser, which is the actually hard part.

How it works

PHP is compiled by php-wasm-builder, and castor app:build puts everything in website/public/build/:

• php-web.wasm and php-web.mjs: PHP 8.5 with the intl extension, compiled with Emscripten, and the application (src/, website/src/ and vendor/), embedded in /app. ICU is statically linked, so there is no intl.so to load with dlopen(): it compiles WebAssembly synchronously, which Chrome refuses on the main thread;
• emoji/: the catalogs of symfony/emoji. They weigh ~37 MB, so the page only fetches the ones it needs (see php.js).

The ICU data (~30 MB) is not shipped: symfony/emoji only needs the \Transliterator class. Anything else that needs the ICU data (Collator, NumberFormatter, IntlDateFormatter…) fails.

For each conversion, the page runs website/src/convert.php with runFile(), gives it the request on stdin, and gets the result on stdout, and the errors on stderr. PHP is started and shut down on each conversion, see the JavaScript API of php-wasm-builder.

Fibers and proc_open() are not supported: Emscripten does not provide the functions they rely on.

Use it in PHP

The converter is a thin layer over symfony/emoji:

use EmojiConverter\EmojiConverter;

$converter = new EmojiConverter();

$converter->fromEmoji('github', 'Hello 👋 🐘'); // Hello :wave: :elephant:
$converter->fromEmoji('fr', 'Hello 👋 🐘'); // Hello signe de la main éléphant
$converter->toEmoji('slack', 'Hello :wave: :elephant:'); // Hello 👋 🐘
$converter->toEmoji('fr', 'Un chat noir, pas un achat'); // Un 🐈‍⬛, pas un achat

symfony/emoji only converts shortcodes back to emoji: names are ordinary words, replacing them with strtr() would also replace them inside other words. The converter replaces whole words only, and prefers the longest name (“chat noir” over “chat”).

Development

You need PHP 8.5+ with intl, Composer, Castor, Docker with Buildx, and Node.js 24+.

castor app:install  # Install the dependencies
castor app:tests    # Run the tests
castor qa:cs        # Fix coding standards
castor qa:phpstan   # Run PHPStan
castor app:build    # Build PHP WebAssembly with the application
castor app:smoke    # Check that what is built boots, and that the page converts
castor app:serve    # Serve the website on http://localhost:9999

The first build takes a few minutes (ICU and PHP are compiled), then only the application is packed again. The website is deployed on GitHub Pages on each push on main, once the tests pass.

License

Emoji Converter is released under the MIT license, see LICENSE. The fonts, Bricolage Grotesque and Space Mono, are released under the SIL Open Font License.