<!DOCTYPE html>
<html>
<body>
<p>Click the button to join three arrays.</p>
<button onclick="myFunction()">Try it</button>
<p id="demo"></p>
<script>
function myFunction() {
var arr1 = ["Cecilie", "Lone"];
var arr2 = ["Emil", "Tobias", "Linus"];
var arr3 = ["Robin", "Morgan"];
document.getElementById("demo").innerHTML =
arr1.concat(arr2, arr3);
}
</script>
</body>
</html>