check phone system

phone-system.js

function getSystem() {
  const isWx = this.isWx()
  const u = navigator.userAgent;

  if(isWx && u.indexOf('Android') > -1){
    return 'aw'
  }
  if (u.indexOf('Android') > -1 || u.indexOf('Linux') > -1) {
    return 'a'
  } else if (u.indexOf('iPhone') > -1) {
    return 'i'
  } else if (u.indexOf('Windows Phone') > -1) {
    return 'w'
  }
}

function isWx() {
  return navigator.userAgent.indexOf('MicroMessenger') > -1 ? true : false
}