[解決済み】JavaScriptでブラウザを検出？重複

navigator.saysWho = (() => {
  const { userAgent } = navigator
  let match = userAgent.match(/(opera|chrome|safari|firefox|msie|trident(?=\/))\/?\s*(\d+)/i) || []
  let temp

  if (/trident/i.test(match[1])) {
    temp = /\brv[ :]+(\d+)/g.exec(userAgent) || []

    return `IE ${temp[1] || ''}`
  }

  if (match[1] === 'Chrome') {
    temp = userAgent.match(/\b(OPR|Edge)\/(\d+)/)

    if (temp !== null) {
      return temp.slice(1).join(' ').replace('OPR', 'Opera')
    }

    temp = userAgent.match(/\b(Edg)\/(\d+)/)

    if (temp !== null) {
      return temp.slice(1).join(' ').replace('Edg', 'Edge (Chromium)')
    }
  }

  match = match[2] ? [ match[1], match[2] ] : [ navigator.appName, navigator.appVersion, '-?' ]
  temp = userAgent.match(/version\/(\d+)/i)

  if (temp !== null) {
    match.splice(1, 1, temp[1])
  }

  return match.join(' ')
})()

console.log(navigator.saysWho) // outputs: `Chrome 89`