es6 string join code example
Example 1: javascript join array
var array = ["Joe", "Kevin", "Peter"];
array.join(); // "Joe,Kevin,Peter"
array.join("-"); // "Joe-Kevin-Peter"
array.join(""); // "JoeKevinPeter"
array.join(". "); // "Joe. Kevin. Peter"
Example 2: join array javascript
<html>
<select multiple class="select-colors">
<option>blue</option>
<option>green</option>
</select>
</html>
<script>
var myColorSelect = $(".select-colors").val().join();
console.log(myColorSelect);
</script>