change background color on button click in javascript

1
2<style>
3  .bg1 {
4  	background-color: red;
5  }
6</style>
7
8<button id="btnChangebgColor" />
9
10<script>
11  	$(document).ready(function(){
12      $("#btnChangebgColor").click(function() {
13        $(this).addClass(".bg1");
14      }); 
15	}
16</script>