Trying to solve some throbbing issues with Safari iPhone

Glitches on Safari iOS #138

Author: dascritch

src/document_cpu.js

@@ -142,12 +142,25 @@ export const DocumentCPU = {
 		}
 
 		if (audiotag.fastSeek) {
-			// HTMLAudioElement.fastSeek() is an experimental but really fast function.
+			// HTMLAudioElement.fastSeek() is an experimental but really fast function. Firefox only, alas
 			audiotag.fastSeek(seconds);
 		} else {
 			try {
+				const settime = () => {audiotag.currentTime = seconds;} ;
 				// Browsers may not have fastSeek but can set currentTime
-				audiotag.currentTime = seconds;
+				if (audiotag.readyState >= audiotag.HAVE_CURRENT_DATA) {
+					// Chrome, Edge, and any other webkit-like except Safari on iPhone
+					settime();
+				} else {
+					// Safari on iPhone is totally incumbent on media throbbing
+					// See https://github.com/dascritch/cpu-audio/issues/138#issuecomment-816526902
+					// and https://stackoverflow.com/questions/18266437/html5-video-currenttime-not-setting-properly-on-iphone
+					audiotag.load();
+				    settime();
+				    if (audiotag.currentTime < seconds){
+				        audiotag.addEventListener("loadedmetadata", settime, {once:true});
+				    }
+				}
 			} catch(e) {
 				// except sometimes, so you must use standard media fragment
 				audiotag.src = `${audiotag.currentSrc.split('#')[0]}#t=${seconds}`;