Untitled

<!DOCTYPE HTML>
<html>

<head>

    <meta charset="UTF-8">


</head>


<body>


          <select id="mySelect[]" name="cars" size="4" multiple>
            <option value="volvo">Volvo</option>
            <option value="saab">Saab</option>
            <option value="fiat">Fiat</option>
            <option value="audi">Audi</option>
          </select>
          <br><br>

<p>to moje auto:</p>


<button onclick="myFunction()">juz wybralem</button>

<p id="demo"></p>

<script>
function myFunction() {
    var ile = document.getElementById("mySelect[]");
    document.getElementById("demo").innerHTML="";
    for (i=0;i<=ile.length;i++){
    var x = ile.options[i].value;
    if (ile.options[i].selected)
    document.getElementById("demo").innerHTML += x+"<br />";
    }
}
</script>


</body>