jQuery: Capitalize first letter while typing inside input field

capitalize_while_inputting.js

<script type="text/javascript" charset="utf-8">
    //Capitalize first letter while typing in side of input field
    jQuery(document).ready(function($) {
        $('#selector').keyup(function(event) {
            var textBox = event.target;
            var start = textBox.selectionStart;
            var end = textBox.selectionEnd;
            textBox.value = textBox.value.charAt(0).toUpperCase() + textBox.value.slice(1);
            textBox.setSelectionRange(start, end);
        });
    });
</script>