Retire.js is a command line scanner that helps you identify dependencies with known vulnerabilites in your application. Using the provided Grunt plugin you can easily include Retire.js into your build process. Retire.js also provides a chrome extension allowing you to detect libraries while surfing your website.
It's important to note that even though your site is using a vulnerable library, that does not necessarily mean your site is vulnerable. It depends on whether and how your site exercises the vulnerable code. That said, it's better to be safe than sorry.