Highlight the typed text that matched the results in jQuery Autocomplete Plugin

Here is my javascript function.I want  to highlight prefixtext into Autocomplete with  Generic Handler.How can i use this javascript function? Which  textbox event  i use for  this function?

 function onClientPopulated(source, eventArgs) {

        if (source._currentPrefix != null) {
            var list = source.get_completionList();
            var search = source._currentPrefix.toLowerCase();
            for (var i = 0; i < list.childNodes.length; i++) {
                var text = list.childNodes[i].innerHTML;
                var index = text.toLowerCase().indexOf(search);
                if (index != -1) {
                    var value = text.substring(0, index);
                    value += '<span style="color:red;font-weight:bold;font-size:16px;">';
                    value += text.substr(index, search.length);
                    value += '</span>';
                    value += text.substring(index + search.length);
                    value = value.replace(/(?:\r\n|\r|\n)/g, '<br />');
                    list.childNodes[i].innerHTML = value;

                }
            }
        }
    }