浏览器内核判断

var ua = navigator.userAgent;
  if(/firefox/i.test(ua)) {
    console.log('火狐内核')
  }else if(/chrome/i.test(ua)) {
    console.log('谷歌内核')
  }else if(/opera/i.test(ua)) {
    console.log('欧朋内核')
  } else if (/msie/i.test(ua)) {
    console.log('ie11以下')
  }else if('ActiveXObject' in window) {
    console.log('ie11')
  }