Need javascript code for button press and hold

Question

I'd like a short smallest possible javascript routine that when a mousedown occurs on a button it first responds just like a mouseclick and then if the user keeps the button pressed it responds as if the user was continously sending mouseclicks and after a while with the button held down acts as if the user was accelerating their mouseclicks...basically think of it like a keypress repeat with acceleration in time.
i.e. user holds down mouse button (x=call function) - x___x___x___x__x__x_x_x_x_xxxxxxx

Answer 1

function holdit(btn, action, start, speedup) {
    var t;

    var repeat = function () {
        action();
        t = setTimeout(repeat, start);
        start = start / speedup;
    }

    btn.mousedown = function() {
        repeat();
    }

    btn.mouseup = function () {
        clearTimeout(t);
    }
};

/* to use */
holdit(btn, function () { }, 1000, 2); /* x..1000ms..x..500ms..x..250ms..x */