Progress bar is usually capped at 100, but you can set any value and max. If value is 0, the bar will be empty.
{%- call ui.util.call(show_example) -%} {%- raw %} {{ ui.progress("Loading..", value=50) }} {{ ui.progress("Not loading", value=0) }} {{ ui.progress(value=10, max=10) }} {%- endraw %} {%- endcall %}