如何检测 Internet Explorer 11 及以下版本？

Question

I'm wondering how I could detect if the user viewing my website is using Internet Explorer 11 or below versions with Javascript.

It should be compatible and works with all these versions.

How to achieve that ?

Answer 1

Here you go, this should work for you:

//Per Icycool, one liner
//function isIE(){
//                 return window.navigator.userAgent.match(/(MSIE|Trident)/);
//               }

function isIE() {
    const ua = window.navigator.userAgent; //Check the userAgent property of the window.navigator object
    const msie = ua.indexOf('MSIE '); // IE 10 or older
    const trident = ua.indexOf('Trident/'); //IE 11
    
    return (msie > 0 || trident > 0);
}


//function to show alert if it's IE
function ShowIEAlert(){
    if(isIE()){
       alert("User is using IE");
    }
}

Answer 2

Check for documentmode - the IE only property:

if (document.documentMode) 
    alert('this is IE');

Answer 3

I'd like to streamline the correct answer. This returns true or false :

function is_IE() {
  return (window.navigator.userAgent.match(/MSIE|Trident/) !== null);
}

Answer 4

Simpler version, returns boolean

function isIE() {
  return !!window.navigator.userAgent.match(/MSIE|Trident/);
}