I took a look at that library and made a quick title showing how it can be used in Lectora.
As you can see, I simply added an HTML extension with a script tag that includes the zxcvbn.js file.
Then, I added the file to the Title.
To see how it works, enter some text in the input box, and click the button. If you look in the developer console of your browser, you will see the object that gets returned from the zxcvbn library. You can take this objects and use it however you need with your title.