JSFiddle - React, Tailwind, and code Playground

HTML

<div></div>
<div></div>

CSS

div { float: left; margin-right: 10px; }
.T { color: #e00000; }

JavaScript

function isPositiveInteger(n) {
    return parseFloat(n) === n >>> 0;
}

$.each([
    "0", "23", "-10", "10.30", "-40.1", "string", "1234567890",
    "129000098131766699.1", "-1e7", "1e7", "1e10", "1edf", " ", ""
], function(i, n) {
    var k = '"' + n + '"', v = isPositiveInteger(n);
    $("<pre />").text(k).toggleClass("T", v).appendTo("div:first");
    $("<pre />").text(":" + v).toggleClass("T", v).appendTo("div:last");
});