I don't get why you're calling submitRandomOrder.bind(this, index). What's the "this" variable pointing to in this context? We're not invoking submitRandomOrder or pauseThenTrade as a method on an object- looks like the "this" variable is just pointing to the global object. If so, what's the point of binding submitRandomOrder to "this"? Please explain the purpose of the bind() call - why is it needed here, and what object is the "this" variable referring to? See http://cl.ly/image/1s460d46132E .