JSFiddle - React, Tailwind, and code Playground

HTML

<div class="thingThatCouldBeOnTop"></div>
<div class="thingThatCouldBeUnderneath"></div>

CSS

div{
    position:absolute;
}

.thingThatCouldBeOnTop{
    width:100px;
    height:100px;
    background-color:#888;
    z-index:2;
}

.thingThatCouldBeUnderneath{
    width:130px;
    height:100px;
    background-color:#ccc;
    z-index:1;
}

JavaScript

$('.thingThatCouldBeOnTop').mouseenter(function(e){
    $('.thingThatCouldBeUnderneath').filter(function(){
        $this = $(this);
        var offset = $this.offset();
        var height = $this.outerHeight();
        var width = $this.outerWidth();
        return offset.top < e.pageY
            && offset.left < e.pageX
            && (height + offset.top) > e.pageY
            && (width + offset.left) > e.pageX;
    }).mouseenter();
});


$('.thingThatCouldBeUnderneath').mouseenter(function(){
    console.log('blarg');
});