JSFiddle - React, Tailwind, and code Playground

by Suryar Praveen

HTML

<input id="seats" type="text" value="aoeu" size="9"/>
<button id="check">Check</button>

JavaScript

$("#check").click(function() {
    var seats = $("#seats").val();

    var error = null;
    
    if (seats == "") {
        error = "Number is required";
    } else {
        var seatsNum = parseInt(seats);
        
        if (isNaN(seatsNum)) {
            error = "Not a valid number";
        } else if (seatsNum >= 99999) {
            error = "Number must be less than 999999";
        }
    }
    
    if (error != null) {
        alert(error);
    } else {
        alert("Valid number");
    }
    
    // If you really need setflag:
    var setflag = error != null;
});