Which browser is running?

Value of navigator.userAgent in each major browser

Firefox

navigator.userAgent
"Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:90.0) Gecko/20100101 Firefox/90.0"

Safari

navigator.userAgent
"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/14.1 Safari/605.1.15"

Chrome

navigator.userAgent
"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.107 Safari/537.36"

Edge

navigator.userAgent
"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.107 Safari/537.36 Edg/92.0.902.55"

Brave

navigator.userAgent
"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.107 Safari/537.36"

navigator.brave

Opera

navigator.userAgent
"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.164 Safari/537.36 OPR/77.0.4054.277"

Code

To determine which browser

function getUserAgent() {
  const userAgent = navigator.userAgent

  // Note: the order matters here
  if (userAgent.includes('OPR/')) return 'opera'
  if (userAgent.includes('Firefox/')) return 'firefox'
  if (userAgent.includes('Edg/')) return 'edge'
  if (navigator.brave) return 'brave'
  if (userAgent.includes('Chrome/')) return 'chrome'
  if (userAgent.includes('Safari/')) return 'safari'
  return undefined
}

To run code coditionally based on browser

function browserSwitch(fnRecord) {
  const userAgent = getUserAgent()
  const fn = fnRecord[userAgent]
  return typeof fn === 'function' && fn()
}

const result = browserSwitch({
  chrome: () => 'this is what you get if running in chrome',
  firefox: () => 'this is what you get if running in firefox',
  edge: () => 'this is what you get if running in edge',
  safari: () => 'this is what you get if running in safari',
  brave: () => 'this is what you get if running in brave',
  opera: () => 'this is what you get if running in opera',
})

console.log(result)