Jquery中给animation加更多的运作效果实例

代码如下:
//animation
jQuery.extend({
    easing:
    {        // ******* back
        backEaseIn: function (p, n, firstNum, diff) {
            var c = firstNum + diff;
            var s = 1.70158; // default overshoot value, can be adjusted to suit
            return c * (p /= 1) * p * ((s + 1) * p - s) + firstNum;
        },
        backEaseOut: function (p, n, firstNum, diff) {
            var c = firstNum + diff;
            var s = 1.70158; // default overshoot value, can be adjusted to suit
            return c * ((p = p / 1 - 1) * p * ((s + 1) * p + s) + 1) + firstNum;
        },
        backEaseInOut: function (p, n, firstNum, diff) {
            var c = firstNum + diff;
            var s = 1.70158; // default overshoot value, can be adjusted to suit
            if ((p /= 0.5) < 1)
                return c / 2 * (p * p * (((s *= (1.525)) + 1) * p - s)) + firstNum;
            else
                return c / 2 * ((p -= 2) * p * (((s *= (1.525)) + 1) * p + s) + 2) + firstNum;
        },
        // ******* bounce
        bounceEaseIn: function (p, n, firstNum, diff) {

            var c = firstNum + diff;
            var inv = this.bounceEaseOut(1 - p, 1, 0, diff);
            return c - inv + firstNum;
        },
        bounceEaseOut: function (p, n, firstNum, diff) {
            var c = firstNum + diff;

            if (p < (1 / 2.75)) {
                return c * (7.5625 * p * p) + firstNum;
            }