`spaceless`

.. warning::

The ``spaceless`` filter is deprecated as of Twig 3.12. While not a full
replacement, you can check the :ref:`whitespace control features <templates-whitespace-control>`.

.. caution::

The ``spaceless`` filter is declared safe for the ``html`` context, so its
output is not auto-escaped. Its input is therefore pre-escaped by the
auto-escaper when needed. If you re-implement this filter in your own
code, declare it with both ``'pre_escape' => 'html'`` and
``'is_safe' => ['html']``: declaring ``is_safe`` without ``pre_escape``
is equivalent to piping user input through ``|raw`` and opens an XSS
vector.

Use the spaceless filter to remove whitespace between HTML tags, not whitespace within HTML tags or whitespace in plain text:

.. code-block:: html+twig

{{
    "<div>
        <strong>foo</strong>
    </div>
    "|spaceless }}

{# output will be <div><strong>foo</strong></div> #}

You can combine spaceless with the apply tag to apply the transformation on large amounts of HTML:

.. code-block:: html+twig

{% apply spaceless %}
    <div>
        <strong>foo</strong>
    </div>
{% endapply %}

{# output will be <div><strong>foo</strong></div> #}

This tag is not meant to "optimize" the size of the generated HTML content but merely to avoid extra whitespace between HTML tags to avoid browser rendering quirks under some circumstances.

.. caution::

As the filter uses a regular expression behind the scenes, its performance
is directly related to the text size you are working on (remember that
filters are executed at runtime).

.. tip::

If you want to optimize the size of the generated HTML content, gzip
compress the output instead.

.. tip::

If you want to create a tag that actually removes all extra whitespace in
an HTML string, be warned that this is not as easy as it seems to be
(think of ``textarea`` or ``pre`` tags for instance). Using a third-party
library like Tidy is probably a better idea.

.. tip::

For more information on whitespace control, read the
:ref:`dedicated section <templates-whitespace-control>` of the documentation and learn how
you can also use the whitespace control modifier on your tags.