$(".foo").css("color", "green");
will actually apply the CSS to all matches. This becomes doubly handy when doing things like attaching event handlers, removing nodes, etc.Looking at Dart's API, I don't see anything like it; queryAll() returns a List<Element>. In order to act on a collection of elements, you have to use iteration mechanisms such as for loops.
The whole concept behind jQuery's $() is that it's a DSL.
Historically, the hardest part of interacting with the DOM has been the inconsistencies (and missing functionality) amongst ancient browser versions. We've had standardized methods for a long time now that make DOM interactions relatively trivial if you have the luxury of working with browsers that support them.
Even newer browsers have a surprising amount of DOM inconsistencies, especially for newer HTML5 APIs that are still evolving. While this is an ongoing job, the Dart DOM API tries hard to polyfill that so that you get a single API that works across most browsers.