JSFiddle - React, Tailwind, and code Playground
HTML
<div id="mydiv" style="display:none;">
<span id="test">test</span>
</div>
<span id="test2">test</span>
JavaScript
console.log( '$("#test").width(): %o ', $("#test").width() );
console.log( '$("#test2").width(): %o ', $("#test2").width() );