debounce, throttle

  function _debounce(callable, wait)
    {
        var id

        function call(context, list)
        {
            requestAnimationFrame(function()
            {
                callable.apply(context, list)
                id = 0
            })
        }

        return function()
        {
            if (id) clearTimeout(id)
            id = setTimeout(call, wait, this, arguments)
        }
    }

    function _throttle(callable, wait)
    {
        var id

        function call(context, list)
        {
            requestAnimationFrame(function()
            {
                callable.apply(context, list)
                id = 0
            })
        }

        return function()
        {
            if (id) return
            id = setTimeout(call, wait, this, arguments)
        }
    }