JSFiddle - React, Tailwind, and code Playground

JavaScript

function isPositiveInteger(val) {
    return val >= 0 && +val % 1 == 0;
}

var tests = [
    "10",
    "-10",
    "10.30",
    "-40.1",
    "string",
    "0",
    "1e10",
    "-1e10",
    "1fd",
    
    "",
    "1290000981231123.1"
    ];

for (var i = 0; i < tests.length; i++) {
    var val = isPositiveInteger(tests[i]);
    $("<pre />").text(tests[i] + ": " + val).appendTo("body");
}