Browser detection in JavaScript? [duplicate]

Answer 1

var isOpera = !!window.opera || navigator.userAgent.indexOf(' OPR/') >= 0;
    // Opera 8.0+ (UA detection to detect Blink/v8-powered Opera)
var isFirefox = typeof InstallTrigger !== 'undefined';   // Firefox 1.0+
var isSafari = Object.prototype.toString.call(window.HTMLElement).indexOf('Constructor') > 0;
    // At least Safari 3+: "[object HTMLElementConstructor]"
var isChrome = !!window.chrome && !isOpera;              // Chrome 1+
var isIE = /*@cc_on!@*/false || !!document.documentMode;
// Edge 20+
var isEdge = !isIE && !!window.StyleMedia;
// Chrome 1+
var output = 'Detecting browsers by ducktyping:
';
output += 'isFirefox: ' + isFirefox + '
';
output += 'isChrome: ' + isChrome + '
';
output += 'isSafari: ' + isSafari + '
';
output += 'isOpera: ' + isOpera + '
';
output += 'isIE: ' + isIE + '
';
output += 'isIE Edge: ' + isEdge + '
';
document.body.innerHTML = output;