Layout.staticUrl ()
render the URL of the directory where images of this layout are located

Sourcecode in Layout/objectFunctions.js:
1:   function staticUrl() {
2:      if (this.site)
3:         this.site.staticUrl();
4:      else
5:         res.write(app.properties.staticUrl);
6:      res.write("layouts/");
7:      res.write(this.alias);
8:      res.write("/");
9:      return;
10:  }