Going beyond automatic SVG compression with the “use” element

Reduce your file size and improve your code.

Link a la versión en español.

If you draw your own SVG files or if you download them from the internet, tools like this SVG-Editor or SVGOMG are your friends. Compressing the files with those tools takes only a few seconds and reduces your file size a lot. But if you need to use your SVG inline to animate or interact with the code, there’s still a lot you can do about code legibility.

Reusing content with SVG’s <use> is not always an option, but when it is, you won’t regret taking a few extra minutes to put it in practice.

In this article, I’ll show an example where I was able to take a lot of advantage of this element — not only for keeping the file size down but also a clearer markup that became more legible and easy to maintain.

This is the first design that I needed to work with. It was originally created in Illustrator:

Take a look at the following code, this is the original file exported directly from the software, weighs 2.05kb:

It’s not a heavy file at all. However, open it and you’ll find there are lots of empty tags, deprecated namespaces, unnecessary white space, commas and extra information applied by the software. This makes the code hard to work with, annoying to scan and creates a big scroll for those hundreds of lines in your document.

You’ll also notice that the file is indeed using <use> and <defs> elements, but not in the best way it could. And that’s not the software’s fault! Each astronaut illustration in the original file has a clipping mask: an invisible circle that acts like a window through which we can see our character. Without it, the suit of the astronaut would be flooding outside the circle. There are a few ways to avoid this in Illustrator, like cropping those extra parts with a pathfinder option. That way we would gain a few bytes and avoid using an extra circle only for…