Optimised search using Ajax and keypress

You can do something like this:

$('#searchString').keyup(function(e) {
    clearTimeout($.data(this, 'timer'));
    if (e.keyCode == 13)
      search(true);
    else
      $(this).data('timer', setTimeout(search, 500));
});
function search(force) {
    var existingString = $("#searchString").val();
    if (!force && existingString.length < 3) return; //wasn't enter, not > 2 char
    $.get('/Tracker/Search/' + existingString, function(data) {
        $('div#results').html(data);
        $('#results').show();
    });
}

What this does is perform a search (on keyup, better than keypress for these situations) after 500ms by storing a timer on the #searchString element's .data() collection. Every keyup it clears that timer, and if the key was enter, searches immediately, if it wasn't sets a another 500ms timeout before auto-searching.

See this older question:

How do I make my live jQuery search wait a second before performing the search?