<script>
function SetText() {
var text = $('#text').val();
$('#textpreview').innerHTML = text;
}
</script>

<input type="text" id="text" value="Введите текст">
<div id="textpreview"></div>
<input type="button" onclick="SetText();" value="Посмотреть">

<input type="text" onkeypress="SetText()" autocomplete="off" id="text" placeholder="Введите текст">
<div id="textpreview"></div>
<script>
function SetText(e) {
    e = e || window.event;
    document.getElementById('textpreview').innerHTML = document.getElementById('text').value + getChar(e);
}
function getChar(event) {
    if (event.which == null) {
        if (event.keyCode < 32) return null;
        return String.fromCharCode(event.keyCode);
    }
    if (event.which!=0 && event.charCode!=0) {
        if (event.which < 32) return null;
        return String.fromCharCode(event.which);
    }
    return null;
}
</script>