(function() {

    let goNum = document.getElementById("goNum");

    goNum.addEventListener("click", function() {

       // gets number and converts them from str to int
        let amount = parseInt(document.getElementById("amount").value);
        let rangeLow = parseInt(document.getElementById("rangeLow").value);
        let rangeHigh = parseInt(document.getElementById("rangeHigh").value);

        // cheks for errors (0, -1..) and the range of span
        if (amount <= 0 || rangeLow <= 0 || rangeHigh <= 0 || (rangeHigh - rangeLow + 1) < amount) { // || means "or"; && means "and"
            resultText.textContent = "ERROR!";
        } else {

            let resultText = document.getElementById("resultText");

            let numArray = [];  // array with rnd numbers

            // if the array numbers are less than requested num -> keep the loop
            for (let i = 0; numArray.length < amount; i++) {
                let randomNum = Math.floor(Math.random() * (rangeHigh - rangeLow + 1)) + rangeLow;

                // if num does not exist in array add it in it
                if (!numArray.includes(randomNum)) { //! means no :)
                    numArray.push(randomNum);
                }
            }

            numArray.sort(function(a, b){return a-b});

            resultText.textContent = numArray.toString(); // toString() converts array into a string

        }

    });

}())