Here is my HTML file

```
<div class="a">
    <div class="b">

    </div>
</div>
<script>
    document.querySelector('.a').onclick = ()=>{
        document.querySelector('.a').style.backgroundColor ='black'
    }
    document.querySelector('.b').onclick = ()=>{
        document.querySelector('.b').style.backgroundColor ='violet'
    }

</script>

```

When I click on the div with class 'b' ,the event handler on the div with class 'a' is also called. I want only the div with 'b' class event handler to be called. Can someone help on this?