An Array inserted via Html tag does not give me the same vlist in multiple cells

Question

Problem code that takes a single array and through the select command of the html it calls me in more cells of the same list, but I tried all the getElement or query, as you can see, only the first cell goes.

Only entering the document.getElementById does the first cell work.

<select id="ku">
    <option>Choose a number</option>    
</select>

<select id="ku">
    <option>Choose a number</option>    
</select>

<select id="ku">
    <option>Choose a number</option>    
</select>


<script>
   
    var select = document.querySelector("select");
    var options = ["kurs1", "Kurs2", "Kurs3", "Kurs4", "Kurs5"];

    for(var i = 0; i < options.length; i++) {
        var opt = options[i];
        var kurse = document.createElement("option");
        kurse.textContent = opt;
        kurse.value = opt;
        select.appendChild(kurse);
}
</script>

Obviously the ids or classes cannot be entered the same, I tried to enter the tag name etc... nothing.

I'm desperate and just starting out with JS. I hope you can help me understand why, thank you.

Answer 1

Use a class instead of duplicating ids. document.querySelectorAll can be used to obtain all elements matching a selector.

const options = ["kurs1", "Kurs2", "Kurs3", "Kurs4", "Kurs5"],
      selects = document.querySelectorAll('select.ku');
for (const option of options)
  for (const select of selects)
    select.add(new Option(option));

<select class="ku">
    <option>Choose a number</option>    
</select>
<select class="ku">
    <option>Choose a number</option>    
</select>
<select class="ku">
    <option>Choose a number</option>    
</select>