sits in the middle of the body, between the client header card and the page's own content. Without defer the HTML parser stops here until the file arrives - and it arrives late, queued behind the whole footer bundle the speculative preload scanner has already started fetching - so the chrome paints and the content area below stays blank for the duration. Measured on vendors.php?client_id=1: document complete at 105ms, this script at 175ms, content painted at 219ms. That ~100ms hole is the flash. defer is safe here: validateClientNameDelete() is only ever called from the onkeyup handler above, and a deferred script is guaranteed to have run before DOMContentLoaded, long before anyone can type. */ ?>