利用requestAnimationFrame和Tween算法实现兼容所有浏览器的运动动画，直接秒杀Css3动画
以下贴出Tween的代码：
/* * Tween.js * t: current time（当前时间）； * b: beginning value（初始值）； * c: change in value（变化量）； * d: duration（持续时间）。 * you can visit 'http://easings.net/zh-cn' to get effect */ var Tween = { Linear: function(t, b, c, d) { return c*t/d + b; }, Quad: { easeIn: function(t, b, c, d) { return c * (t /= d) * t + b; }, easeOut: function(t, b, c, d) { return -c *(t /= d)*(t-2) + b; }, easeInOut: function(t, b, c, d) { if ((t /= d / 2) < 1) return c / 2 * t * t + b; return -c / 2 * ((--t) * (t-2) - 1) + b; } }, Cubic: { easeIn: function(t, b, c, d) { return c * (t /= d) * t * t + b; }, easeOut: function(t, b, c, d) { return c * ((t = t/d - 1) * t * t + 1) + b; }, easeInOut: function(t, b, c, d) { if ((t /= d / 2) < 1) return c / 2 * t * t*t + b; return c / 2*((t -= 2) * t * t + 2) + b; } }, Quart: { easeIn: function(t, b, c, d) { return c * (t /= d) * t * t*t + b; }, easeOut: function(t, b, c, d) { return -c * ((t = t/d - 1) * t * t*t - 1) + b; }, easeInOut: function(t, b, c, d) { if ((t /= d / 2) < 1) return c / 2 * t * t * t * t + b; return -c / 2 * ((t -= 2) * t * t*t - 2) + b; } }, Quint: { easeIn: function(t, b, c, d) { return c * (t /= d) * t * t * t * t + b; }, easeOut: function(t, b, c, d) { return c * ((t = t/d - 1) * t * t * t * t + 1) + b; }, easeInOut: function(t, b, c, d) { if ((t /= d / 2) < 1) return c / 2 * t * t * t * t * t + b; return c / 2*((t -= 2) * t * t * t * t + 2) + b; } }, Sine: { easeIn: function(t, b, c, d) { return -c * Math.cos(t/d * (Math.PI/2)) + c + b; }, easeOut: function(t, b, c, d) { return c * Math.sin(t/d * (Math.PI/2)) + b; }, easeInOut: function(t, b, c, d) { return -c / 2 * (Math.cos(Math.PI * t/d) - 1) + b; } }, Expo: { easeIn: function(t, b, c, d) { return (t==0) ? b : c * Math.pow(2, 10 * (t/d - 1)) + b; }, easeOut: function(t, b, c, d) { return (t==d) ? b + c : c * (-Math.pow(2, -10 * t/d) + 1) + b; }, easeInOut: function(t, b, c, d) { if (t==0) return b; if (t==d) return b+c; if ((t /= d / 2) < 1) return c / 2 * Math.pow(2, 10 * (t - 1)) + b; return c / 2 * (-Math.pow(2, -10 * --t) + 2) + b; } }, Circ: { easeIn: function(t, b, c, d) { return -c * (Math.sqrt(1 - (t /= d) * t) - 1) + b; }, easeOut: function(t, b, c, d) { return c * Math.sqrt(1 - (t = t/d - 1) * t) + b; }, easeInOut: function(t, b, c, d) { if ((t /= d / 2) < 1) return -c / 2 * (Math.sqrt(1 - t * t) - 1) + b; return c / 2 * (Math.sqrt(1 - (t -= 2) * t) + 1) + b; } }, Elastic: { easeIn: function(t, b, c, d, a, p) { var s; if (t==0) return b; if ((t /= d) == 1) return b + c; if (typeof p == "undefined") p = d * .3; if (!a || a < Math.abs(c)) { s = p / 4; a = c; } else { s = p / (2 * Math.PI) * Math.asin(c / a); } return -(a * Math.pow(2, 10 * (t -= 1)) * Math.sin((t * d - s) * (2 * Math.PI) / p)) + b; }, easeOut: function(t, b, c, d, a, p) { var s; if (t==0) return b; if ((t /= d) == 1) return b + c; if (typeof p == "undefined") p = d * .3; if (!a || a < Math.abs(c)) { a = c; s = p / 4; } else { s = p/(2*Math.PI) * Math.asin(c/a); } return (a * Math.pow(2, -10 * t) * Math.sin((t * d - s) * (2 * Math.PI) / p) + c + b); }, easeInOut: function(t, b, c, d, a, p) { var s; if (t==0) return b; if ((t /= d / 2) == 2) return b+c; if (typeof p == "undefined") p = d * (.3 * 1.5); if (!a || a < Math.abs(c)) { a = c; s = p / 4; } else { s = p / (2 *Math.PI) * Math.asin(c / a); } if (t < 1) return -.5 * (a * Math.pow(2, 10* (t -=1 )) * Math.sin((t * d - s) * (2 * Math.PI) / p)) + b; return a * Math.pow(2, -10 * (t -= 1)) * Math.sin((t * d - s) * (2 * Math.PI) / p ) * .5 + c + b; } }, Back: { easeIn: function(t, b, c, d, s) { if (typeof s == "undefined") s = 1.70158; return c * (t /= d) * t * ((s + 1) * t - s) + b; }, easeOut: function(t, b, c, d, s) { if (typeof s == "undefined") s = 1.70158; return c * ((t = t/d - 1) * t * ((s + 1) * t + s) + 1) + b; }, easeInOut: function(t, b, c, d, s) { if (typeof s == "undefined") s = 1.70158; if ((t /= d / 2) < 1) return c / 2 * (t * t * (((s *= (1.525)) + 1) * t - s)) + b; return c / 2*((t -= 2) * t * (((s *= (1.525)) + 1) * t + s) + 2) + b; } }, Bounce: { easeIn: function(t, b, c, d) { return c - Tween.Bounce.easeOut(d-t, 0, c, d) + b; }, easeOut: function(t, b, c, d) { if ((t /= d) < (1 / 2.75)) { return c * (7.5625 * t * t) + b; } else if (t < (2 / 2.75)) { return c * (7.5625 * (t -= (1.5 / 2.75)) * t + .75) + b; } else if (t < (2.5 / 2.75)) { return c * (7.5625 * (t -= (2.25 / 2.75)) * t + .9375) + b; } else { return c * (7.5625 * (t -= (2.625 / 2.75)) * t + .984375) + b; } }, easeInOut: function(t, b, c, d) { if (t < d / 2) { return Tween.Bounce.easeIn(t * 2, 0, c, d) * .5 + b; } else { return Tween.Bounce.easeOut(t * 2 - d, 0, c, d) * .5 + c * .5 + b; } } } } Math.tween = Tween;
requestAnimationFrame兼容性代码：
(function() { var lastTime = 0; var vendors = ['webkit', 'moz']; for(var x = 0; x < vendors.length && !window.requestAnimationFrame; ++x) { window.requestAnimationFrame = window[vendors[x] + 'RequestAnimationFrame']; window.cancelAnimationFrame = window[vendors[x] + 'CancelAnimationFrame'] || // name has changed in Webkit window[vendors[x] + 'CancelRequestAnimationFrame']; } if (!window.requestAnimationFrame) { window.requestAnimationFrame = function(callback, element) { var currTime = new Date().getTime(); var timeToCall = Math.max(0, 16.7 - (currTime - lastTime)); var id = window.setTimeout(function() { callback(currTime + timeToCall); }, timeToCall); lastTime = currTime + timeToCall; return id; }; } if (!window.cancelAnimationFrame) { window.cancelAnimationFrame = function(id) { clearTimeout(id); }; } }());
调用方式和setTime类似
实际案例：
<!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>requestAnimationFrame实现皮球落地的缓动效果</title> <script> document.createElement("ball"); document.createElement("shadow"); </script> <style> .demo { height: 600px; position: relative; } h4 { text-align: center; font-size: 110%; } ball { width: 100px; height: 100px; border-radius: 100px; position: absolute; left: 50%; top: 500px; margin-left: -50px; background-color: #34538b; background-image: -webkit-radial-gradient(100px 100px at 50px 20px, #a0b3d6, #34538b); background-image: -moz-radial-gradient(100px 100px at 50px 20px, #a0b3d6, #34538b); background-image: radial-gradient(100px 100px at 50px 20px, #a0b3d6, #34538b); cursor: move; z-index: 1; } shadow { position: absolute; width: 100px; height: 30px; position: absolute; left: 50%; bottom: 5px; margin-left: -50px; background-image: -webkit-radial-gradient(ellipse closest-side, rgba(0,0,0,.75), rgba(0,0,0,0)); background-image: -moz-radial-gradient(ellipse closest-side, rgba(0,0,0,.75), rgba(0,0,0,0)); background-image: radial-gradient(ellipse closest-side, rgba(0,0,0,.75), rgba(0,0,0,0)); } </style> </head> <body> <div id="main"> <h1>requestAnimationFrame实现皮球落地的缓动效果实例页面</h1> <div id="body" class="light"> <div id="content" class="show"> <h3>展示</h3> <div class="demo"> <h4>向上拖动小球然后放下</h4> <ball></ball><shadow></shadow> </div> </div> </div> </div> <script src="js/jquery.min.js"></script> <script src="js/requestAnimationFrame.js"></script> <script src="js/tween.js"></script> <script> var ball = $("ball"), shadow = $("shadow"); var objBall = {}; var shadowWithBall = function(top) { // 0 ~ 500 var top = top || parseInt(ball.css("top")), scale = 1 + (500 - top) / 500; opacity = 1 - (500 - top) / 500; if (opacity < 0) opacity = 0; shadow.css("opacity", opacity) .css("WebkitTransform", "scale("+ [scale, scale].join(",") +")") .css("transform", "scale("+ [scale, scale].join(",") +")"); }, funFall = function() { var start = 0, during = 100; var _run = function() { start++; var top = Tween.Bounce.easeOut(start, objBall.top, 500 - objBall.top, during); ball.css("top", top); shadowWithBall(top); if (start < during) requestAnimationFrame(_run); }; _run(); }; ball.bind("mousedown", function(event) { objBall.pageY = event.pageY; objBall.flagFollow = true; }); $(document).bind("mousemove", function(event) { if (objBall.flagFollow) { var pageY = event.pageY; console.log(objBall.pageY + " === " + pageY); objBall.top = 500 - (objBall.pageY - pageY); if (objBall.top < 0) { objBall.top = 0; } else if (objBall.top > 500) { objBall.top = 500; } //cosnole.log(objBall.top); ball.css("top", objBall.top); shadowWithBall(objBall.top); } }); $(document).bind("mouseup", function(event) { if (objBall.flagFollow) funFall(); objBall.flagFollow = false; }); </script> </body> </html>
