在页面中实现运动的四种方式

1.速度版：

function startMove(obj,json,fnEnd){
    if(obj.timer){
        clearInterval(obj.timer);
    }
    obj.timer = setInterval(function(){
        doMove(obj,json,fnEnd);
    },30);
}
function doMove(obj,json,fnEnd){
    var iCur = 0;
    var attr = null;
    var bStop = true;
    for(attr in json){
        if(attr=='opacity'){
            iCur = parseInt(100*parseFloat(getStyle(obj,attr)));
        }
        else{
            iCur = parseInt(getStyle(obj,attr));
        }
        var iSpeed = (json[attr] - iCur)/8;
        iSpeed = iSpeed>0 ? Math.ceil(iSpeed) : Math.floor(iSpeed);
        if(json[attr]!=iCur){
            bStop = false;
        }
        if(attr=='opacity'){
            obj.style.filter = 'alpha(opacity='+ (iCur + iSpeed) +')';
            obj.style.opacity = (iCur + iSpeed)/100;
        }
        else{
            obj.style[attr] = iCur + iSpeed + 'px';
        }
    }
    if(bStop){
        clearInterval(obj.timer);
        obj.timer = null;
        if(fnEnd){
            fnEnd();
        }
    }
}
function getStyle(obj,attr){
    if(obj.currentStyle){
        return obj.currentStyle[attr];
    }
    else{
        return getComputedStyle(obj)[attr];
    }
}

速度版运动框架有个小问题，不是代码的问题，而是浏览器本身的功能问题。当运动途中，切换页面或缩小浏览器窗口后，浏览器会自动放慢页面中所有的定时器，这样可能会导致页面中的定时器出问题：比如有的定时器有回调函数，有的定时器没有，当重新切换回原来的页面时，有回调函数的定时器可能回调会来不及执行，造成页面中定时器的混乱状态，影响页面的效果。如果是一个简单的轮播图效果，我们可以使用如下代码简单处理下：

window.onfocus = function(){
    console.log(1);
    timer = setInterval(toRun,2000);
};

window.onblur = function(){
    console.log(2);
    clearInterval(timer);
};

2.时间版：

function startMove(obj,json,times,fx,fn){
    
    if( typeof times == 'undefined' ){
        times = 400;
        fx = 'linear';
    }
    
    if( typeof times == 'string' ){        
        if(typeof fx == 'function'){
            fn = fx;
        }
        fx = times;
        times = 400;
    }
    else if(typeof times == 'function'){
        fn = times;
        times = 400;
        fx = 'linear';
    }
    else if(typeof times == 'number'){
        if(typeof fx == 'function'){
            fn = fx;
            fx = 'linear';
        }
        else if(typeof fx == 'undefined'){
            fx = 'linear';
        }
    }
    
    var iCur = {};
    for(var attr in json){
        iCur[attr] = 0;
        attr == 'opacity' ? iCur[attr] = Math.round(getStyle(obj,attr)*100) : iCur[attr] = parseInt(getStyle(obj,attr));
    }
    
    var startTime = now();    
    clearInterval(obj.timer);
    
    obj.timer = setInterval(function(){
        
        var changeTime = now();     
        var t = times - Math.max(0,startTime - changeTime + times);  
        
        for(var attr in json){
            
            var value = Tween[fx](t,iCur[attr],json[attr]-iCur[attr],times);
            
            if(attr == 'opacity'){
                obj.style.opacity = value/100;
                obj.style.filter = 'alpha(opacity='+value+')';
            }
            else{
                obj.style[attr] = value + 'px';
            }
            
        }
        
        if(t == times){ 
            clearInterval(obj.timer);
            fn && fn.call(obj); 
        }
        
    },20);
    
    function getStyle(obj,attr){ return obj.currentStyle ? obj.currentStyle[attr] : getComputedStyle(obj,false)[attr]; }
    function now(){ return (new Date()).getTime(); }    
};

var Tween = {
    linear: function (t, b, c, d){  //匀速
        return c*t/d + b;
    },
    easeIn: function(t, b, c, d){  //加速曲线
        return c*(t/=d)*t + b;
    },
    easeOut: function(t, b, c, d){  //减速曲线
        return -c *(t/=d)*(t-2) + b;
    },
    easeBoth: function(t, b, c, d){  //加速减速曲线
        if ((t/=d/2) < 1) {
            return c/2*t*t + b;
        }
        return -c/2 * ((--t)*(t-2) - 1) + b;
    },
    easeInStrong: function(t, b, c, d){  //加加速曲线
        return c*(t/=d)*t*t*t + b;
    },
    easeOutStrong: function(t, b, c, d){  //减减速曲线
        return -c * ((t=t/d-1)*t*t*t - 1) + b;
    },
    easeBothStrong: function(t, b, c, d){  //加加速减减速曲线
        if ((t/=d/2) < 1) {
            return c/2*t*t*t*t + b;
        }
        return -c/2 * ((t-=2)*t*t*t - 2) + b;
    },
    elasticIn: function(t, b, c, d, a, p){  //正弦衰减曲线（弹动渐入）
        if (t === 0) { 
            return b; 
        }
        if ( (t /= d) == 1 ) {
            return b+c; 
        }
        if (!p) {
            p=d*0.3; 
        }
        if (!a || a < Math.abs(c)) {
            a = c; 
            var s = p/4;
        } else {
            var 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;
    },
    elasticOut: function(t, b, c, d, a, p){    //正弦增强曲线（弹动渐出）
        if (t === 0) {
            return b;
        }
        if ( (t /= d) == 1 ) {
            return b+c;
        }
        if (!p) {
            p=d*0.3;
        }
        if (!a || a < Math.abs(c)) {
            a = c;
            var s = p / 4;
        } else {
            var 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;
    },    
    elasticBoth: function(t, b, c, d, a, p){
        if (t === 0) {
            return b;
        }
        if ( (t /= d/2) == 2 ) {
            return b+c;
        }
        if (!p) {
            p = d*(0.3*1.5);
        }
        if ( !a || a < Math.abs(c) ) {
            a = c; 
            var s = p/4;
        }
        else {
            var s = p/(2*Math.PI) * Math.asin (c/a);
        }
        if (t < 1) {
            return - 0.5*(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 )*0.5 + c + b;
    },
    backIn: function(t, b, c, d, s){     //回退加速（回退渐入）
        if (typeof s == 'undefined') {
           s = 1.70158;
        }
        return c*(t/=d)*t*((s+1)*t - s) + b;
    },
    backOut: function(t, b, c, d, s){
        if (typeof s == 'undefined') {
            s = 3.70158;  //回缩的距离
        }
        return c*((t=t/d-1)*t*((s+1)*t + s) + 1) + b;
    }, 
    backBoth: 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;
    },
    bounceIn: function(t, b, c, d){    //弹球减振（弹球渐出）
        return c - Tween['bounceOut'](d-t, 0, c, d) + b;
    },       
    bounceOut: 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 + 0.75) + b;
        } else if (t < (2.5/2.75)) {
            return c*(7.5625*(t-=(2.25/2.75))*t + 0.9375) + b;
        }
        return c*(7.5625*(t-=(2.625/2.75))*t + 0.984375) + b;
    },      
    bounceBoth: function(t, b, c, d){
        if (t < d/2) {
            return Tween['bounceIn'](t*2, 0, c, d) * 0.5 + b;
        }
        return Tween['bounceOut'](t*2-d, 0, c, d) * 0.5 + c*0.5 + b;
    }
}

时间版函数是基于Tween的扩展，利用了Tween的运动样式，当然jQuery也是基于Tween的时间版运动，但是并没有扩展Tween中的更多的运动形式，如果需要，我们还可以扩展jQuery的运动形式，编写一个扩展jQuery的运动插件。

3.jQuery运动插件扩展：

$.extend(jQuery.easing , {
    
    easeIn: function(x,t, b, c, d){  //加速曲线
        return c*(t/=d)*t + b;
    },
    easeOut: function(x,t, b, c, d){  //减速曲线
        return -c *(t/=d)*(t-2) + b;
    },
    easeBoth: function(x,t, b, c, d){  //加速减速曲线
        if ((t/=d/2) < 1) {
            return c/2*t*t + b;
        }
        return -c/2 * ((--t)*(t-2) - 1) + b;
    },
    easeInStrong: function(x,t, b, c, d){  //加加速曲线
        return c*(t/=d)*t*t*t + b;
    },
    easeOutStrong: function(x,t, b, c, d){  //减减速曲线
        return -c * ((t=t/d-1)*t*t*t - 1) + b;
    },
    easeBothStrong: function(x,t, b, c, d){  //加加速减减速曲线
        if ((t/=d/2) < 1) {
            return c/2*t*t*t*t + b;
        }
        return -c/2 * ((t-=2)*t*t*t - 2) + b;
    },
    elasticIn: function(x,t, b, c, d, a, p){  //正弦衰减曲线（弹动渐入）
        if (t === 0) { 
            return b; 
        }
        if ( (t /= d) == 1 ) {
            return b+c; 
        }
        if (!p) {
            p=d*0.3; 
        }
        if (!a || a < Math.abs(c)) {
            a = c; 
            var s = p/4;
        } else {
            var 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;
    },
    elasticOut: function(x,t, b, c, d, a, p){    //正弦增强曲线（弹动渐出）
        if (t === 0) {
            return b;
        }
        if ( (t /= d) == 1 ) {
            return b+c;
        }
        if (!p) {
            p=d*0.3;
        }
        if (!a || a < Math.abs(c)) {
            a = c;
            var s = p / 4;
        } else {
            var 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;
    },    
    elasticBoth: function(x,t, b, c, d, a, p){
        if (t === 0) {
            return b;
        }
        if ( (t /= d/2) == 2 ) {
            return b+c;
        }
        if (!p) {
            p = d*(0.3*1.5);
        }
        if ( !a || a < Math.abs(c) ) {
            a = c; 
            var s = p/4;
        }
        else {
            var s = p/(2*Math.PI) * Math.asin (c/a);
        }
        if (t < 1) {
            return - 0.5*(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 )*0.5 + c + b;
    },
    backIn: function(x,t, b, c, d, s){     //回退加速（回退渐入）
        if (typeof s == 'undefined') {
           s = 1.70158;
        }
        return c*(t/=d)*t*((s+1)*t - s) + b;
    },
    backOut: function(x,t, b, c, d, s){
        if (typeof s == 'undefined') {
            s = 3.70158;  //回缩的距离
        }
        return c*((t=t/d-1)*t*((s+1)*t + s) + 1) + b;
    }, 
    backBoth: function(x,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;
    },
    bounceIn: function(x,t, b, c, d){    //弹球减振（弹球渐出）
        return c - this['bounceOut'](x,d-t, 0, c, d) + b;
    },       
    bounceOut: function(x,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 + 0.75) + b;
        } else if (t < (2.5/2.75)) {
            return c*(7.5625*(t-=(2.25/2.75))*t + 0.9375) + b;
        }
        return c*(7.5625*(t-=(2.625/2.75))*t + 0.984375) + b;
    },      
    bounceBoth: function(x,t, b, c, d){
        if (t < d/2) {
            return this['bounceIn'](x,t*2, 0, c, d) * 0.5 + b;
        }
        return this['bounceOut'](x,t*2-d, 0, c, d) * 0.5 + c*0.5 + b;
    }
    
});

当页面需要扩展jQuery运动形式时，可以直接把这个代码拷在我们自己写的js文件中。

4.animation动画：

@-moz-keyframes btnPage { 
  0% { -moz-transform: translateY(6px); }
  50% { -moz-transform: translateY(0); }
  100% { -moz-transform: translateY(6px); } 
}
@-webkit-keyframes btnPage { 
  0% { -webkit-transform: translateY(6px); }
  50% { -webkit-transform: translateY(0); }
  100% { -webkit-transform: translateY(6px); } 
}
@keyframes btnPage { 
  0% { transform: translateY(6px); }
  50% { transform: translateY(0); }
  100% { transform: translateY(6px); } 
}
/*btn-page*/
.btn-page { 
    position: fixed; 
    _position: absolute; 
    z-index: 100; 
    left: 50%; 
    bottom: 30px; 
    _bottom: auto; 
    margin-left: -12px; 
    width: 25px; 
    height: 17px; 
    overflow: hidden; 
    cursor: pointer; 
    background-position: 0 -18px; 
    _top: expression(eval(document.documentElement.scrollTop+document.documentElement.clientHeight-this.offsetHeight -30)); 
    -moz-animation: btnPage 1.2s ease-in-out infinite; 
    -webkit-animation: btnPage 1.2s ease-in-out infinite; 
    animation: btnPage 1.2s ease-in-out infinite; 
}

当我们的页面需要添加CSS3动画时，只需要定义好关键帧和运动的名称，然后把这个运动名称引入我们需要的class里面，就可以利用js动态的添加或改变CSS3动画了。