如何使用 javascript 遍歷這個數組？

Question

鑒於此腳本：

<html>
<head>

<script>
var sentences= 
[
 ['journey27.mp4', 
  [
    [1, 2],
    [5, 7]
  ]
 ],
 ['journey28.mp4', 
  [
    [10, 12],
    [13, 17],
    [25, 36]
  ]
 ],
 ['journey30.mp4', 
  [
    [13, 15],
    [15, 19],
    [21, 30]
  ]
 ]
];

function playVideo(myUrl, startTime, endTime) { 
  var video = document.getElementById("myVideo");
  video.src = myUrl;
  video.currentTime=startTime;
  video.play();

  var maxTime = endTime;
  video.addEventListener("timeupdate", function(){
    if(video.currentTime >= maxTime){
     playVideo(myUrl, startTime, endTime);
    }
  }, false);
} 

function myLoop(){
  I want to loop each pairs 5 times before jump to the next pair
}
</script>
</head>
<body>
<video id="myVideo" width="1000" height="800" controls autoplay loop>

  Your browser does not support the video tag.
</video>

<br>
<a  onclick="myLoop()" > Play </a>

</body>
</html>

現在我要填寫myLoop function。

我想在跳轉到數組中的下一對之前循環每對 5 次。

例如，-第一對：'journey27.mp4'，循環“ [1, 2] ”5次

然后是下一對：'journey27.mp4'，循環“ [5, 7] ”5 次