/*** 惯性原理:* 产生的速度 = 移动距离 / 移动时间* 距离 = 松开的坐标 - 上次的坐标  (距离差)* 时间 = 松开的时间 - 按下的时间  (时间差)* */var dargFun = {dargDom:null, //惯性滑动的DOM区域startX:0, //开始偏移的XstartY:0, //开始偏移的YclientX:0, clientY:0,translateX:0, //保存的X偏移translateY:0, //保存的Y偏移maxWidth:0, //滑动的最大宽度maxHeight:0, //滑动的最大高度startTime:0, //记录初始按下时间init:function(config){this.dargDom = document.querySelector(config.dargDom);this.maxWidth = this.dargDom.offsetWidth;this.maxHeight = this.dargDom.offsetHeight;this.dargDom.addEventListener('touchstart',(event)=>{event.stopPropagation(); //停止事件传播this.clientX = event.changedTouches[0].clientX;this.clientY = event.changedTouches[0].clientY;this.dargDom.style.WebkitTransition = this.dargDom.style.transition = '';this.startX = this.translateX;this.startY = this.translateY;this.startTime = Date.now();},false);this.dargDom.addEventListener('touchmove',(event)=>{if(document.documentElement.scrollTop >= this.dargDom.scrollHeight - this.dargDom.clientHeight){}else{return;}event.stopPropagation(); //停止事件传播this.translateX = event.changedTouches[0].clientX - this.clientX + this.startX;this.translateY = event.changedTouches[0].clientY - this.clientY + this.startY;if(this.translateY > 0 ){ //拖动系数. 拉力的感觉this.translateY *= 0.4;}else if( this.translateY < -(this.dargDom.scrollHeight - this.dargDom.clientHeight)){ this.translateY = (event.changedTouches[0].clientY - this.clientY) * 0.4 + this.startY;}this.animate(this.translateY);},false);this.dargDom.addEventListener('touchend',(event)=>{event.stopPropagation(); //停止事件传播var distanceY = event.changedTouches[0].clientY - this.clientY,timeDis = Date.now() - this.startTime,  //时间差speed = (distanceY / timeDis) * 100;// 惯性this.translateY += speed;this.translateY  = 0;// 添加贝塞尔曲线this.dargDom.style.WebkitTransition = this.dargDom.style.transition = 'transform 500ms cubic-bezier(0.1, 0.57, 0.1, 1)';this.animate(this.translateY);},false);},animate:function(y){this.dargDom.style.WebkitTransform = this.dargDom.style.transform = 'translateY('+y+'px)';}
}export default dargFun;

dragFun.init({dargDom:'#contractContanier'
});