<script>
    function ile()
    {
        var text1 = document.getElementById('text1');
        var text2 = document.getElementById('text2');
        //
        text2.value = text1.value.length;
    }
    function wytnij()
    {
        var text1 = document.getElementById('text1');
        var text2 = document.getElementById('text2');
        var number1 = document.getElementById('number1');
        var number2 = document.getElementById('number2');
        //
        text2.value = text1.value.slice(number1.value, number2.value);
    }
    function maleduze()
    {
        var text1 = document.getElementById('text1');
        var text2 = document.getElementById('text2');
        var male = document.getElementById('male');
        //
        if (!male.checked) text2.value = text1.value.toLowerCase();
        else text2.value = text1.value.toUpperCase();
    }
</script>
<form>
    Text 1: <input type="text" id=text1 value="Ala ma kota!" onkeyup="wytnij()"><br>
    Text 2: <input type="text" id=text2><br>
    X1: <input type="number" id="number1" value="0" onchange="wytnij()" style="width: 50px;">
    X2: <input type="number" id="number2" value="3" onchange="wytnij()" style="width: 50px;"><br>
    <input type="button" value="ile jest znaków w text1", onclick="ile()"><br>
    <input type="button" value="wytnij z text1" onclick="wytnij()"><br>
    <input type="checkbox" id=male> małe/Duże litery
    <input type="button" value="małe duże litery z text1" onclick="maleduze()"><br>
</form>