In the context of javascript, "unobtrusive" means it is designed to degrade peacefully in browsers where javascript is missing or disabled. In this case, the right way to attach an event handler is to assign a class or an id to the HTML element in question and add an event handler to it using an event listener in a separate javascript file, rather than jamming an `onclick="doSomething()"` attribute into the HTML element itself.
> In the context of javascript, "unobtrusive" means it is designed to degrade peacefully
Nitpicking here, but that is actually graceful degradation/progressive enhancement.
Unobtrusive JavaScript is about writing JavaScript code that plays well with others. The example you gave of not having inline JavaScript in your presentation layer (HTML) is one example. Not writing JS code in the global namespace and avoiding monkey-patching built-in objects are other examples.
