collapsespaces is a Django template tag that collapses whitespace characters between tags into one space. This fork also strips leading whitespace on any new line and any whitespace between HTML attributes (e.g. id="foo" class="bar").

collapsespacestag.py

"""
collapsespaces is a Django template tag that collapses whitespace characters between tags into one space.

It is based on Django's 'spaceless' template tag (spaceless is different in that it completely removes whitespace between tags).

Why is this important?
Given "<span>5</span> <span>bottles</span>", collapsespaces will preserve the space between the two span elements--spaceless will not.
In a web browser:
"<span>5</span> <span>bottles</span>" renders as "5 bottles"
"<span>5</span><span>bottles</span>" renders as "5bottles"
"""

import re
from django import template
from django.utils.encoding import force_unicode
from django.utils.functional import allow_lazy

register = template.Library()

def collapse_spaces_between_tags(value):
    """Returns the given HTML with whitespaces collapsed to one space."""
    # Collapse all leading spaces at the beginning of a line (credit: https://djangosnippets.org/snippets/547/)
    value = re.sub(r'\n\s+', '\n', force_unicode(value)) 
    # Collapse whitespace between attributes inside HTML tags (thanks to https://regex101.com/)
    value = re.sub(r'\s+([\w-]*?=\"[^\"]*?\")', r' \1', force_unicode(value))
    # Collapse whitespace between tags
    value = re.sub(r'\s+<', r' <', force_unicode(value))
    value = re.sub(r'>\s+', r'> ', force_unicode(value))
    return value

collapse_spaces_between_tags = allow_lazy(collapse_spaces_between_tags, unicode)


class CollapseSpacesNode(template.Node):
    def __init__(self, nodelist):
        self.nodelist = nodelist

    def render(self, context):
        return collapse_spaces_between_tags(self.nodelist.render(context).strip())


def collapsespaces(parser, token):
    """
    Collapses whitespace between HTML tags into one space.

    Example usage::
        {% load collapsespacestag %}
        {% collapsespaces %}
            <p>
               <a href="foo/"
                  class="bar">
                     Foo
               </a>
            </p>
        {% endcollapsespaces %}

    This example would return this HTML::

        <p> <a href="foo/" class="bar"> Foo </a> </p>
    """
    nodelist = parser.parse(('endcollapsespaces',))
    parser.delete_first_token()
    return CollapseSpacesNode(nodelist)
collapsespaces = register.tag(collapsespaces)