Twig Components / Methods / spaceless

spaceless is a Twig 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.

Source: Twig