JSFiddle - React, Tailwind, and code Playground

HTML

<div class="div1">TEST</div>
<div class="div2">OTHER</div>
<div class="div3">THIRD</div>

CSS

div
{
    padding: 10px;
    border: 1px solid black;
}

.div2, .div3
{
    width: 40%;
    float: left;
}

JavaScript

$( function() {
    $('.div1').mouseleave( function(e) {
        if( ! $(e.toElement).hasClass('div2') ) {
            alert( 'not div2!' );
        }
    });
});