SOURCE

let oOne = document.querySelector(".one")
let oTwo = document.querySelector(".two")
let oThree = document.querySelector(".three")
oOne.onclick = function(){
    alert("one")
}
oTwo.onclick = function(){
    alert("two")
}
oThree.onclick = function(){
    alert("three")
}

<div class="one">
    <div class="two">
        <div class="three"></div>
    </div>
</div>

.one{
  width:400px;
  height:400px;
  background:#f00
    
}
.two{
  width:300px;
  height:300px;
  background:#f60;
}
.three{
  width:200px;
  height:200px;
  background:#ccc
}