微信小程序如何实现简单文字跑马灯

 
 
 
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.container {display: flex;flex-direction: column;justify-content: space-between;box-sizing: border-box;}
.scrolltxt{padding:0 20rpx;background:#f8f8f8;}
.marquee_box {position:relative;color:#333;height:90rpx;display:block;overflow:hidden;} 
.marquee_text {white-space: nowrap;position:absolute;top:0;font-size:14px;height:90rpx;line-height:90rpx;}

 data: {
 //滚动字幕
 text: "温馨提示：为了保证其他购买者的利益，每个 账号针对同一商品只允许退款一次，请您谨慎操作。",
 marqueePace: 1,//滚动速度
 marqueeDistance: 0,//初始滚动距离
 marquee_margin: 30,//间距
 size: 14,//字号
 time: '',// 定时器
 },

onHide: function () {
 //清空滚动字幕定时器，避免锁屏或页面隐藏后移动速度越来越快
 clearInterval(this.data.time);
 },

 onShow: function (e) {
 var that = this;
 var length = that.data.text.length * that.data.size;//文字长度
 var windowWidth = wx.getSystemInfoSync().windowWidth;// 屏幕宽度
 //console.log(length,windowWidth);
 that.setData({
 length: length,
 windowWidth: windowWidth
 });
 that.scrolltxt();// 第一个字消失后立即从右边出现
 },

 /**
 * 滚动字幕
 */
 scrolltxt: function () {
 var that = this;
 var length = that.data.length;//滚动文字的宽度
 var windowWidth = that.data.windowWidth;//屏幕宽度
 var time = this.data.time
 if (length > windowWidth) {
 time = setInterval(function () {
 var maxscrollwidth = length + that.data.marquee_margin;//滚动的最大宽度，文字宽度+间距，如果需要一行文字滚完后再显示第二行可以修改marquee_margin值等于windowWidth即可
 var crentleft = that.data.marqueeDistance;
 if (crentleft < maxscrollwidth) {//判断是否滚动到最大宽度
  that.setData({
  marqueeDistance: crentleft + that.data.marqueePace
  })
 }
 else {
  that.setData({
  marqueeDistance: 0 // 直接重新滚动
  });
  clearInterval(time);
  that.scrolltxt();
 }
 }, 20);
 }
 else {
 that.setData({ marquee_margin: "1000" });//只显示一条不滚动右边间距加大，防止重复显示
 }
 that.setData({
 time:time
 })
 },