I recoginzed that i can use
$('span') even when no js-framework is loaded.
It works in FF, Chrome and Edge. Where does this function come from? I had never read about it. Is it a HTML5 feature?
It's an alias for
document.querySelector() provided by browser's developer tools. This shorthand is not available for page's JS code.
There are more useful dollar-tools, most notably
$0 which contains a reference to DOM element selected in inspector.