I have developed a Node.JS library that implements many of the USPS Publication 28 guidelines in the form of an address building class. It accepts multiple fields of address inputs, and then builds a USPS compatible address.
I plan to add many more features, including a parsing function to decompose address strings back into their components.
Let me know what you think!
NPM page: npmjs.org/package/node-usps
GitHub source: github.com/daball/node-usps