index1.html

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<title>Untitled Document</title>
<script src="https://unpkg.com/vue"></script>
<script>
window.onload = function() {
new Vue({
el : "#app",
data : {
message : "hello world"
}
})

var app5= new Vue ({
el : "#app5",
data : {
          message : "click function"
} ,
methods : {
       reversefunction : function()
	   {
	   this.message= "click is done";
	   }
}

})
}
</script>
</head>

<body>
<div id="app">
<p> {{message}} </p></div>

<div id="app5">
<p>{{ message }}</p>
<button v-on:click="reversefunction"> click me </button>
</div>

</body>
</html>