# `html_classes`

The `html_classes` function returns a string by conditionally joining class names together:

    <p class="{{ html_classes('a-class', 'another-class', {
        'errored': object.errored,
        'finished': object.finished,
        'pending': object.pending,
    }) }}">How are you doing?</p>

Note

The `html_classes` function is part of the `HtmlExtension` which is not installed by default. Install it first:

    $ composer require twig/html-extra

Then, on Symfony projects, install the `twig/extra-bundle`:

    $ composer require twig/extra-bundle

Otherwise, add the extension explicitly on the Twig environment:

    use Twig\Extra\Html\HtmlExtension;

    $twig = new \Twig\Environment(...);
    $twig->addExtension(new HtmlExtension());