[nostrademons]

I always viewed design patterns as a communication tool between programmers. Saying

  $('.button .link .pulldown')
     .addClass('active')
     .on('hover', highlight)
     .on('click', doSomething);

is quite a mouthful. But if everyone's familiar with design patterns, then you can just say "Oh, it's a Builder pattern" and everybody knows what you're talking about. Same goes for many, many other situations; familiarity with MVC will go a long way towards understanding angular.js, and familiarity with Chain of Responsibility will teach you about WSGI or Django Middleware, or the State pattern will help you understand trampolines in interpreter implementation.