bufferWhenNeeded stops loading anything when manually jumping to a different time in video about netfix HOT 3 OPEN

  var assetURL = "frag_bunny.mp4";
  var mimeCodec = 'video/mp4; codecs="avc1.42E01E, mp4a.40.2"';
  var totalSegments;
  var segmentLength = 0;
  var segmentDuration = 0;
  var seeking = false;
  var bytesFetched = 0;

  var requestedSegments = [];

  var mediaSource = null;
  if ("MediaSource" in window && MediaSource.isTypeSupported(mimeCodec)) {
    mediaSource = new MediaSource();
    video.src = URL.createObjectURL(mediaSource);
    mediaSource.addEventListener("sourceopen", sourceOpen);
  } else {
    console.error("Unsupported MIME type or codec: ", mimeCodec);
  }
  var sourceBuffer = null;

  function sourceOpen(_) {
    sourceBuffer = mediaSource.addSourceBuffer(mimeCodec);
    sourceBuffer.mode = "sequence";
    getFileLength(assetURL, function(fileLength) {
      // console.log((fileLength / 1024 / 1024).toFixed(2), "MB");
      totalSegments = (fileLength / 1024 / 1024).toFixed(0);
      for (var i = 0; i < totalSegments; ++i) requestedSegments[i] = false;

      segmentLength = Math.round(fileLength / totalSegments);

      fetchRange(assetURL, 0, segmentLength, appendSegment);
      requestedSegments[0] = true;
      video.addEventListener("timeupdate", checkBuffer);
      video.addEventListener("canplay", function() {
        segmentDuration = video.duration / totalSegments;
        const promise = video.play();
        if (promise !== undefined) {
          promise
            .then(_ => {
              console.log(_);
              // Autoplay started!
            })
            .catch(error => {
              // Autoplay was prevented.
              // Show a "Play" button so that user can start playback.
            });
        }
      });

      video.addEventListener("seeking", debounce(handleSeek, 500));
      video.addEventListener("seeked", onSeeked);
    });
  }

  function debounce(func, wait, immediate) {
    var timeout;
    return function() {
      var context = this;
      var args = arguments;
      var later = function() {
        timeout = null;
        if (!immediate) func.apply(context, args);
      };
      var callNow = immediate && !timeout;
      clearTimeout(timeout);
      timeout = setTimeout(later, wait);
      if (callNow) func.apply(context, args);
    };
  }

  function getFileLength(url, cb) {
    var xhr = new XMLHttpRequest();
    xhr.open("head", url);
    xhr.onload = function() {
      cb(xhr.getResponseHeader("content-length"));
    };
    xhr.send();
  }

  function onSeeked() {
    console.log("seeked");
  }

  function fetchRange(url, start, end, cb) {
    return new Promise((resolve, reject) => {
      var xhr = new XMLHttpRequest();
      xhr.open("get", url);
      xhr.responseType = "arraybuffer";
      xhr.setRequestHeader("Range", "bytes=" + start + "-" + end);
      xhr.onload = function() {
        console.log("fetched bytes: ", start, end);
        bytesFetched += end - start + 1;
        resolve(cb(xhr.response));
      };
      xhr.send();
    });
  }

  function appendSegment(chunk) {
    return sourceBuffer.appendBuffer(chunk);
  }

  async function checkBuffer() {
    console.log("check Buffer");
    if (seeking) {
      return true;
    }
    var nextSegment = getNextSegment();
    if (nextSegment === totalSegments && haveAllSegments()) {
      mediaSource.endOfStream();
      video.removeEventListener("timeupdate", checkBuffer);
    } else if (shouldFetchNextSegment(nextSegment)) {
      requestedSegments[nextSegment] = true;

      await fetchRange(
        assetURL,
        bytesFetched,
        bytesFetched + segmentLength,
        appendSegment
      );
    }
  }

  async function handleSeek() {
    console.log("seeking");
    seeking = true;
    var nextSegment = getNextSegment();
    if (nextSegment === totalSegments && haveAllSegments()) {
      mediaSource.endOfStream();
      video.removeEventListener("timeupdate", checkBuffer);
    } else {
      // sourceBuffer.abort();
      for (let segment = 1; segment < nextSegment; segment++) {
        if (shouldFetchNextSegment(segment)) {
          requestedSegments[segment] = true;

          // console.log({ bytesFetched, next: bytesFetched + segmentLength });

          await fetchRange(
            assetURL,
            bytesFetched,
            bytesFetched + segmentLength,
            appendSegment
          );
        }
      }
    }
    seeking = false;
  }

  function seek(e) {
    if (mediaSource.readyState === "open") {
      handleSeek();
    } else {
      console.log("seek but not open?");
      console.log(mediaSource.readyState);
    }
  }

  function getNextSegment() {
    return ((video.currentTime / segmentDuration) | 0) + 1;
  }

  function haveAllSegments() {
    return requestedSegments.every(function(val) {
      return !!val;
    });
  }

  function shouldFetchNextSegment(nextSegment) {
    // console.log(nextSegment);
    // console.log({
    //   nextSegment,
    //   currentTime: video.currentTime,
    //   val: segmentDuration * nextSegment * 0.1,
    //   bool: requestedSegments[nextSegment]
    // });
    return (
      video.currentTime > segmentDuration * nextSegment * 0.1 &&
      requestedSegments[nextSegment] == false
    );
  }`