The PHP module has its own filesystem separate from your computer’s filesystem. It is provided by Emscripten’s FS library and the default APIs is low-level and cumbersome to use. The PHP JavaScript class shipped with WordPress Playground wraps it with a more convenient higher-level API.
In general, WordPress Playground uses an in-memory virtual filesystem.
However, in Node.js, you can also mount a real directory from the host filesystem into the PHP filesystem.
Here’s how to interact with the filesystem in WordPress Playground:
// Recursively create a /var/www directory
php.mkdirTree('/var/www');
console.log(php.fileExists('/var/www/file.txt'));
// false
php.writeFile('/var/www/file.txt', 'Hello from the filesystem!');
console.log(php.fileExists('/var/www/file.txt'));
// true
console.log(php.readFile('/var/www/file.txt'));
// "Hello from the filesystem!
// Delete the file:
php.unlink('/var/www/file.txt');For more details consult the BasePHP class directly โ it has some great documentation strings.