In some cases, getting an element with the core functionality of the DOM is not very useful. The alternative way is to access an element with interfaces of the SVG module. The interfaces in the SVG module are called specific interfaces. With specific interfaces, you can access elements like definitions with <desc> more quickly. However, you must not check where and how often an element occurs.
Using specific interfaces is sometimes the faster way to access elements. But are there interfaces for all-important SVG elements? Yes, more or less for all SVG elements. The base interface for most of the others is SVGElement. It contains all elements of an SVG graphic. Other interfaces inherit from SVGElement.