useage of nested this (JS)

nestedThis.html

<input type="button" value="A" id="buttonA" >
<input type="button" value="B" id="buttonB" >
<script>
var objectA = new function () {
    this.alertMessage = "Hello world!";
    this.ClickHandler = function() {
        alert(this.alertMessage );
  }
};
document.getElementById("buttonA").onclick =  objectA.ClickHandler //undefined

var objectB = new function () {
    var self = this;
    this.alertMessage = "Hello world!";
    this.ClickHandler = function() {
        alert(self.alertMessage);
    }
};
document.getElementById("buttonB").onclick =  objectB.ClickHandler //Hello world!
</script>