微信小程序实现跑马灯效果

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Page({ /**  * 页面的初始数据  */ data: {  interval: null,  text: '995年JavaScript诞生时如早一年',  pace: 1.2, //滚动速度  interval: 20, //时间间隔  size: 24, //字体大小in px  length: 0, //字体宽度  offsetLeft: 0, //  windowWidth: 0, }, //根据viewId查询view的宽度 queryViewWidth: function(viewId) {  //创建节点选择器  return new Promise(function(resolve) {   var query = wx.createSelectorQuery();   var that = this;   query.select('.' + viewId).boundingClientRect(function(rect) {    resolve(rect.width);   }).exec();  }); }, //停止跑马灯 stopMarquee: function() {  var that = this;  //清除旧的定时器  if (that.data != null) {   clearInterval(that.interval);  } }, //执行跑马灯动画 excuseAnimation: function() {  var that = this;  if (that.data.length > that.data.windowWidth) {   //设置循环   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);  } }, //开始跑马灯 startMarquee: function() {  var that = this;  that.stopMarquee();  //初始化数据  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();  }); } })