JSFiddle - React, Tailwind, and code Playground

HTML

<div></div>

CSS

div {
width: 20em;
height: 20em;
-o-transition: width 0.3s ease-in-out;
-ms-transition: width 0.3s ease-in-out;
-moz-transition: width 0.3s ease-in-out;
-webkit-transition: width 0.3s ease-in-out;
background: pink;
}

JavaScript

function checkFontZoom(event){
    if( $("div:eq(0)").width() != (20 * 8) ){
        $("div:eq(0)").text("i was zoomed")
    }
}

$("div:eq(0)")[0].addEventListener( 
     'webkitTransitionEnd', 
     checkFontZoom, false );