JSFiddle - React, Tailwind, and code Playground

JavaScript

var str = "12.345";
    var m = str.match(/^\d{0,2}(?:\.\d{0,2}){0,1}$/);
    var goodTime;
    if (!m) {
        alert(str + " is not a good time");
    }
    else {
        goodTime = m[0];
        alert("found a good time: " + goodTime);
    }