How to check the user is using Internet Explorer in JavaScript?

There may arise cases when we need to check the browser being used. Some features of your website may not be supported in older browsers like Internet Explorer(IE). There are different ways to check the version of Internet Explorer being used.

Syntax-1: For Internet Explorer 10 or older

var ua = window.navigator.userAgent;
var msie = ua.indexOf('MSIE ');
if (msie > 0) {
   // IE 10 or older => return version number
        return parseInt(ua.substring(msie + 5, ua.indexOf('.', msie)), 10);
    }

Syntax-2: For Internet Explorer 11

var ua = window.navigator.userAgent;
var trident = ua.indexOf('Trident/');
if (trident > 0) {
        // IE 11 => return version number
        var rv = ua.indexOf('rv:');
        return parseInt(ua.substring(rv + 3, ua.indexOf('.', rv)), 10);
    }

Syntax-3: For Internet Explorer 12+ (Edge)

var ua = window.navigator.userAgent;
var edge = ua.indexOf('Edge/');
if (edge > 0) {
       // Edge (IE 12+) => return version number
       return parseInt(ua.substring(edge + 5, ua.indexOf('.', edge)), 10);
    }

Example:

Output (Opening with Firefox):

Not IE

Output (Opening with IE 11):

IE 11

Output (Opening with Edge):

IE 18