JSFiddle - React, Tailwind, and code Playground

HTML

<span id="spn" style="line-height: normal;">

JavaScript

var spn = document.getElementById("spn");
var computedStyle = getComputedStyle(spn, null);
try {
    alert(computedStyle.lineHeight + ", " + computedStyle.getPropertyCSSValue("line-height").getFloatValue(5));
} catch (e) {
    alert(computedStyle.lineHeight + ", " + e);
}