PianoTime/wechat/pages/index/index.js

var app = getApp()
Page({
  
  onLoad: function () {
    console.log('onLoad')
    wx.getSystemInfo({
      success: (res) => {
        this.setData({
          screenWidth: res.screenWidth,
          screenHeight: res.screenHeight,
          bannerWidth: res.screenWidth,
          bannerHeight: res.screenWidth * 363 / 543
        })
      }
    })
  }
})