用策略思维做的小球滑动
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<script>var tween = {linear: function (t, b, c, d) {return c * t / d + b;},easeIn: function (t, b, c, d) {return c * (t /= d) * t + b;},strongEaseIn: function (t, b, c, d) {return c * (t /= d) * t * t * t * t + b;},strongEaseOut: function (t, b, c, d) {return c * ((t = t / d - 1) * t * t * t * t + 1) + b;},sineaseIn: function (t, b, c, d) {return c * (t /= d) * t * t + b;},sineaseOut: function (t, b, c, d) {return c * ((t = t / d - 1) * t * t + 1) + b;}};var Animate = function (dom) {this.dom = dom; // 进行运动的dom 节点this.startTime = 0; // 动画开始时间this.startPos = 0; // 动画开始时，dom 节点的位置，即dom 的初始位置this.endPos = 0; // 动画结束时，dom 节点的位置，即dom 的目标位置this.propertyName = null; // dom 节点需要被改变的css 属性名this.easing = null; // 缓动算法this.duration = null; // 动画持续时间};Animate.prototype.start = function (propertyName, endPos, duration, easing) {this.startTime = +new Date; // 动画启动时间this.startPos = this.dom.getBoundingClientRect()[propertyName]; // dom 节点初始位置this.propertyName = propertyName; // dom 节点需要被改变的CSS 属性名this.endPos = endPos; // dom 节点目标位置this.duration = duration; // 动画持续事件this.easing = tween[easing]; // 缓动算法var self = this;var timeId = setInterval(function () { // 启动定时器，开始执行动画if (self.step() === false) { // 如果动画已结束，则清除定时器clearInterval(timeId);}}, 16);};Animate.prototype.step = function () {var t = +new Date; // 取得当前时间if (t >= this.startTime + this.duration) { // (1)this.update(this.endPos); // 更新小球的CSS 属性值return false;}var pos = this.easing(t - this.startTime, this.startPos, this.endPos - this.startPos, this.duration);// pos 为小球当前位置this.update(pos); // 更新小球的CSS 属性值};Animate.prototype.update = function (pos) {this.dom.style[this.propertyName] = pos + 'px';};var div = document.getElementById('div');var animate = new Animate(div);animate.start('left', 500, 1000, 'linear');// animate.start( 'top', 1500, 500, 'strongEaseIn' );
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