There's a hosted version of dygraphs on UNPKG:

<link rel="stylesheet" type="text/css" href="https://unpkg.com/dygraphs@2.2.2/dist/dygraph.min.css" />
<script type="text/javascript" src="https://unpkg.com/dygraphs@2.2.2/dist/dygraph.min.js"></script>

There's a hosted version of dygraphs on jsDelivr:

<link rel="stylesheet" type="text/css" href="https://cdn.jsdelivr.net/npm/dygraphs@2.2.2/dist/dygraph.min.css" />
<script type="text/javascript" src="https://cdn.jsdelivr.net/npm/dygraphs@2.2.2/dist/dygraph.min.js"></script>

Note: if you wish to use jsDelivr’s ESM feature, you need to replace import * as dygraphs from 'https://esm.run/dygraphs';, which is the string they give you, with import Dygraph from 'https://esm.run/dygraphs';, i.e. replace the * as dygraphs part with Dygraph so to have that symbol available.
You’ll also still need to include the CSS separately.

There's a hosted version of dygraphs on cdnjs.com (note that it may take some time to update to new releases):

<link rel="stylesheet" type="text/css" href="//cdnjs.cloudflare.com/ajax/libs/dygraph/2.2.2/dygraph.min.css" />
<script type="text/javascript" src="//cdnjs.cloudflare.com/ajax/libs/dygraph/2.2.2/dygraph.min.js"></script>

But note that use of CDNs violates the EU-GDPR.

Besides the tarballs (see above) you can also install dygraphs locally into your project instead using NPM:

$ npm install dygraphs
  # dygraphs is now in node_modules/dygraphs/dist/dygraph.{css,js} for
  # the browser, and node_modules/dygraphs/index{,.es5}.js for nodejs

There’s also a Debian package available:

$ sudo apt-get install libjs-dygraphs
  # dygraphs is now in /usr/share/javascript/dygraphs/dygraph.{css,js}

  # To access the documentation locally, run in a terminal:
$ cd /usr/share/doc/libjs-dygraphs/site && python3 -m http.server
  # Navigate to http://127.0.0.1:8000/ while this is running.

  # When a webserver is running, do:
$ sudo apt-get install javascript-common
$ sudo a2enconf javascript-common.conf && sudo service apache2 reload
  # dygraphs is now also available at /javascript/dygraphs/dygraph.{css,js}
  # so it can be used from webpages served by the system in question

To generate your own minified JS, install the prerequisites…

• mksh
• pax
• python3

… and run:

git clone https://github.com/danvk/dygraphs.git
cd dygraphs
npm install
npm run build-jsonly

This will create a dygraph.min.css and a dygraph.min.js file in the dist directory.

Building and testing the full distribution is slightly more intricate.