optimized search using ajax and keypress

Question

i have the following code as i want to search a database as a user is typing into a textbox. This code below works fine but it seems a little inefficient as if a user is typing really fast, i am potentially doing many more searches than necessary. So if a user is typing in "sailing"

i am searching on "sail", "saili", "sailin", and "sailing"

i wanted to see if there was a way to detect any particular time between keypresses so only search if user stops typing for 500 milliseconds or something like this.

is there a best practices for something like this?

$('#searchString').keypress(function(e) {

    if (e.keyCode == 13) {

        var url = '/Tracker/Search/' + $("#searchString").val();
        $.get(url, function(data) {
            $('div#results').html(data);
            $('#results').show();
        });
    }
    else {

        var existingString = $("#searchString").val();
        if (existingString.length > 2) {
            var url = '/Tracker/Search/' + existingString;
            $.get(url, function(data) {
                $('div#results').html(data);
                $('#results').show();
            });
        }
    }

Answer 1

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.

Answer 2

What I would do is each key press use a setTimeout function with the desired delay. So that function will fire after that timeout. Each key press then delete the timer and set a new one, with clearTimeout();

See here for some examples, scrolling past all the adverts.

http://www.elated.com/articles/javascript-timers-with-settimeout-and-setinterval/

Answer 3

See this older question:

http://stackoverflow.com/questions/1171582/how-do-i-make-my-live-jquery-search-wait-a-second-before-performing-the-search