be-based is a package that allows a DOM document fragment filled with relative URL paths, to be adjusted based on a base URL. This is quite critical when streaming HTML from a third-party element to a DOM node contained within the Live DOM tree. be-based plays a critical role in combination with be-written.

<div be-based="https://www.supremecourt.gov/about/">
    <a href="biographies.aspx#SOConnor">O'Connor, Sandra Day</a>
<div>

is shorthand for:

<div be-based='{
    "base": "https://www.supremecourt.gov/about/",
    "forAll": ["href", "src", "xlink:href"]
}'>
    <a href="biographies.aspx#SOConnor">O'Connor, Sandra Day</a>
</div>

be-based rewrites the attribute within:

<div is-based="https://www.supremecourt.gov/about/">
    <a href="https://www.supremecourt.gov/about/biographies.aspx#SOConnor">O'Connor, Sandra Day</a>
</div>

be-based is one of a growing family of be-hive/be-enhanced web component based custom attributes / behaviors / decorators / directives.

By referencing behivior.js, elements with attribute be-based will be discovered and transformed.

If using stream-orator to stream HTML to a target element, be-based can be used to watch all new elements, and apply all the rules as they are discovered.

This seems to work quite well with Chromium based browsers running on windows (rewriting image url's before the browser tries the original, invalid url), but isn't so effective with Firefox.

Update: Well, on Chromium based browsers, it doesn't seem so reliable either, at least depending on when I try.

W3C willing.