JavaScript problem with duplicate images js html

[lap]

i have this script that is showing my images randomly but i dont know how to stop the images being duplicates , im very new to js and would greatly apreciate any help thank you

<table cellpadding="0" cellspacing="0" width="100%">
   <tr>
    <td><img src "" class="img"></td>
    <td><img src "" class="img"></td>
    <td><img src "" class="img"></td>
  </tr>
 <tr>
    <td><img src "" class="img"></td>
    <td><img src "" class="img"></td>
    <td><img src "" class="img"></td>
  </tr>
  <tr>
    <td><img src "" class="img"></td>
    <td><img src "" class="img"></td>
    <td><img src "" class="img"></td>
  </tr>
           
</table>
           
             <script>
      window.onload = function() {
  let myPics = ['images/img correct/1.jpg',
                'images/img correct/2.jpg',
                'images/img correct/3.jpg',
                'images/img correct/4.jpg',
                'images/img correct/5.jpg',
                'images/img correct/6.jpg',
                'images/img correct/7.jpg',
                'images/img correct/8.jpg',
                'images/img correct/9.jpg',
                'images/img correct/10.jpg',
                'images/img correct/11.jpg',
                'images/img correct/12.jpg',
                'images/img correct/13.jpg',
                'images/img correct/14.jpg',
                'images/img correct/15.jpg',
                'images/img correct/16.jpg',
                'images/img correct/17.jpg',
                'images/img correct/18.jpg',
  ];

  function showPics() {
    document.querySelectorAll('.img').forEach(function(tag) {
      let index = getRandomIndex();
      tag.src = myPics[index];
      tag.addEventListener('click', getImageName);
      tag.dataset.index = index;
    })
  }

  function getRandomIndex() {
    return Math.floor(Math.random() * myPics.length);
  }

  function getImageName() {
     alert(myPics[this.dataset.index])
  }

  showPics();
}
    </script>

 

[Deleted member 2829]

Picking a random number 18 times from the range [1..18] is guaranteed to produce some duplicates. You would be better off doing a random shuffle of the array, so you can just loop through it and get all different images in random order. This post https://stackoverflow.com/questions/2450954/how-to-randomize-shuffle-a-javascript-array mentions several ways to random shuffle an array.