reader/pages/message/index.js

const app = getApp()
Page({
  data: {
    menu: {
      show: true,
      top: 0,
      left: 0
    }
  },
  onLoad(options) {

  },
  onShow() {
    if (typeof this.getTabBar === 'function') {
      this.getTabBar().setData({
        selected: 3
      })
    }
  },
  onLongPress(e) {
    console.log(e);
    let {
      currentTarget,
      detail,
      touches,
      target
    } = e
    let remainingW = app.globalData.windowWidth - touches[0].clientX
    let remainingH = app.globalData.windowHeight - touches[0].clientY
    let wFlag = remainingW - 145 > 0
    let hFlag = remainingH - 200 > 0
    this.setData({
      menu: {
        show: true,
        top: hFlag ? e.detail.y : e.detail.y - 100,
        left: wFlag ? e.detail.x : e.detail.x - 135
      }
    })
  }
})