JSFiddle - React, Tailwind, and code Playground

HTML

<form id='sampleform' method='get' action=''>
    Guess: <input type='text' name='guess' id = 'guess'/>
    <button id ='b1' type="submit">Submit</button>
</form>

JavaScript

document.getElementById('sampleform').addEventListener('submit', checkForm);

    x = Math.floor(Math.random()*99)

    function randomNumber(){
        return x;
    }


    function checkForm(/*event*/ e) {

        e.preventDefault();
        var number = document.getElementById('guess').value; 

        if (number == null || number == "" || isNaN(number) || number < 0 || number > 99){

            alert("Invalid input");
            return false;
        }
        else if (number == x)
        {
            alert("You're correct!");
            document.getElementById('b1').disabled = true;
            return true;
        }
        else {
            alert("Wrong! Try again.")
        }
    }

    randomNumber();
    console.log(x); //checks value for testing