How to check if a div class has been clicked in JavaScript?

I want to check if a div class element has been clicked.Is there a way in Javascript. I have a conditional statement which checked whether a style has certain attributes, but there is no way I know of checking whether a div class in that conditional statement has been clicked…

Here’s my code so far:

let a = document.getElementsByClassName("roll")[0];
let b = document.getElementsByClassName("effect")[0];

a.onclick = function(){
    b.setAttribute('style','border-right:4px solid #aa2e27')
}

a.onmouseover = function(){
    if(b.hasAttribute('style','border-right:none') && a.onclick.value == "false"){
        b.setAttribute('style','border-right:4px solid #aa2e27');
    }
}

As you can see, the if condition takes place on mouseover event. Is there a way to check this? (what I entered on mouseover doesnt trigger)