JSFiddle - React, Tailwind, and code Playground

HTML

<p class="some-class">Test</p>

CSS

.some-class {
    line-height: 2px; }

JavaScript

var height = $(".some-class").css("line-height");
if (height !== "normal") {
   height = height.replace(/px$/, ""); 
    if (height < 18) {
        alert("The height (" + height + ") is less than 18");
    } else {
        alert("The height (" + height + ") is greater or equal to 18");
    }
} else {
    alert("The height is " + height);
}