spaceless

Warning

The spaceless filter is deprecated as of Twig 3.12. While not a full replacement, you can check the whitespace control features.

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:

{{
    "<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:

{% 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 dedicated section of the documentation and learn how you can also use the whitespace control modifier on your tags.