WebProgramming: EventListener und DOM Element, Callback function, Fetch API

20250422 function id(id) { return document.getElementById(id); } function qs(selector) { return document.querySelector(selector); } function qsa(selector) { return document.querySelectorAll(selector); } settimeout wsetinterval, Error first callbascks? error und result promise(fallbackfunction) =resolve() reject()