text: function getLocalAddr(){
    let os = require('os')
    let interfaces = os.networkInterfaces()
    let localIntf = null; 
    for(let intname in interfaces){
      let intf = interfaces[intname];
      let find = intf.some(entry=>{
        if(entry.family !== 'IPv4' || entry.internal){
          return
        }
        localIntf = entry
      })
      if(find){
        break
      }
    }
    return localIntf.address
  }
  module.exports = getLocalAddr