<input id="txt" type="text" />
<span id="changeCount">0</span>

$('#txt').keydown(function(event) {
    // Don't count the keys which don't actually change
    // the text. The four below are the arrow keys, but
    // there are more that I omitted for brevity.
    if (event.which != 37 && event.which != 38 &&
        event.which != 39 && event.which != 40) {

        // Replace the two lines below with whatever you want to
        // do when the text changes.
        var count = parseInt($('#changeCount').text(), 10) + 1;
        $('#changeCount').text(count);

    }
});

var i = 0;
$('#text').bind('check_changed', function(){
    var t = $(this);

    // do something after certain interval, for better performance
    delayRun('my_text', function(){
        var pv = t.data('prev_val');

        // if previous value is undefined or not equals to the current value then blablabla
        if(pv == undefined || pv != t.val()){
            $('#count').html(++i);
            t.data('prev_val', t.val());
        }
    }, 1000);
})
// if the textbox is changed via typing
.keydown(function(){$(this).trigger('check_changed')})
// if the textbox is changed via 'paste' action from mouse context menu
.bind('paste', function(){$(this).trigger('check_changed')});

// clicking the flush button can force all pending functions to be run immediately
// e.g., if you want to submit the form, all delayed functions or validations should be called before submitting.
// delayRun.flush() is the method for this purpose
$('#flush').click(function(){ delayRun.flush(); });

;(function(g){
    var delayRuns = {};
    var allFuncs = {};

    g.delayRun = function(id, func, delay){
        if(delay == undefined) delay = 200;
        if(delayRuns[id] != null){
            clearTimeout(delayRuns[id]);
            delete delayRuns[id];
            delete allFuncs[id];
        }
        allFuncs[id] = func;
        delayRuns[id] = setTimeout(function(){
            func();
            delete allFuncs[id];
            delete delayRuns[id];
        }, delay);
    };

    g.delayRun.flush = function(){
        for(var i in delayRuns){
            if(delayRuns.hasOwnProperty(i)){
                clearTimeout(delayRuns[i]);
                allFuncs[i]();
                delete delayRuns[i];
                delete allFuncs[i];
            }
        }
    };
})(window);