<view class="rollCon"> <view class='box'>  <view class='text'style='left:{{offsetLeft}}px' >{{text}}</view></view></view>

.rollCon { position: fixed; top: 0; left: 0; width: 100%; height: 60rpx; z-index: 100; background: #fde8c7; font-size: 20rpx; line-height: 60rpx;}.box { width: 100%; position: relative;}.text { white-space: nowrap; position: absolute; top: 0; font-size: 24px;}

Page({ /**  * 頁面的初始數據  */ data: {  interval: null,  text: '995年JavaScript誕生時如早一年',  pace: 1.2, //滾動速度  interval: 20, //時間間隔  size: 24, //字體大小in px  length: 0, //字體寬度  offsetLeft: 0, //  windowWidth: 0, }, //根據viewId查詢view的寬度 queryViewWidth: function(viewId) {  //創建節點選擇器  return new Promise(function(resolve) {   var query = wx.createSelectorQuery();   var that = this;   query.select('.' + viewId).boundingClientRect(function(rect) {    resolve(rect.width);   }).exec();  }); }, //停止跑馬燈 stopMarquee: function() {  var that = this;  //清除舊的定時器  if (that.data != null) {   clearInterval(that.interval);  } }, //執行跑馬燈動畫 excuseAnimation: function() {  var that = this;  if (that.data.length > that.data.windowWidth) {   //設置循環   let interval = setInterval(function() {    if (that.data.offsetLeft <= 0) {     if (that.data.offsetLeft >= -that.data.length) {      that.setData({       offsetLeft: that.data.offsetLeft - that.data.pace,      })     } else {      that.setData({       offsetLeft: that.data.windowWidth,      })     }    } else {     that.setData({      offsetLeft: that.data.offsetLeft - that.data.pace,     })    }   }, that.data.interval);  } }, //開始跑馬燈 startMarquee: function() {  var that = this;  that.stopMarquee();  //初始化數據  that.data.windowWidth = wx.getSystemInfoSync().windowWidth;  that.queryViewWidth('text').then(function(resolve) {   that.data.length = resolve;   console.log(that.data.length + "/" + that.data.windowWidth);   that.excuseAnimation();  }); } })