Angular 2 How to show warning page if browser is unsupported

Question

I have a problem with demonstrating warning page, if Angular 2 app doesn't support browser. I have tried to use routing system, but actually it didn't help. Here is my index page. How can I redirect(show to user) warning page if browser is unsupported? Maybe I need add some extra script to body, but what about <app> tag?

<!DOCTYPE html>
<html>
<head>
    <base href="/">
</head>
<body>
    <app>Loading...</app>
</body>
</html>

Duplicate ?: https://stackoverflow.com/questions/36877151/angular-2-check-whether-users-browser-is-compatible — Vega, Sep 08 '17 at 13:46

Krzysztof Raciniewski · Accepted Answer · 2019-03-25T18:16:04.637

I think you should use clear JavaScript code:

var BrowserDetect = {
        init: function () {
            this.browser = this.searchString(this.dataBrowser) || "Other";
            this.version = this.searchVersion(navigator.userAgent) || this.searchVersion(navigator.appVersion) || "Unknown";
        },
        searchString: function (data) {
            for (var i = 0; i < data.length; i++) {
                var dataString = data[i].string;
                this.versionSearchString = data[i].subString;

                if (dataString.indexOf(data[i].subString) !== -1) {
                    return data[i].identity;
                }
            }
        },
        searchVersion: function (dataString) {
            var index = dataString.indexOf(this.versionSearchString);
            if (index === -1) {
                return;
            }

            var rv = dataString.indexOf("rv:");
            if (this.versionSearchString === "Trident" && rv !== -1) {
                return parseFloat(dataString.substring(rv + 3));
            } else {
                return parseFloat(dataString.substring(index + this.versionSearchString.length + 1));
            }
        },

        dataBrowser: [
            {string: navigator.userAgent, subString: "Edge", identity: "MS Edge"},
            {string: navigator.userAgent, subString: "MSIE", identity: "Explorer"},
            {string: navigator.userAgent, subString: "Trident", identity: "Explorer"},
            {string: navigator.userAgent, subString: "Firefox", identity: "Firefox"},
            {string: navigator.userAgent, subString: "Opera", identity: "Opera"},  
            {string: navigator.userAgent, subString: "OPR", identity: "Opera"},  

            {string: navigator.userAgent, subString: "Chrome", identity: "Chrome"}, 
            {string: navigator.userAgent, subString: "Safari", identity: "Safari"}       
        ]
    };
    
    BrowserDetect.init();
    document.write("You are using <b>" + BrowserDetect.browser + "</b> with version <b>" + BrowserDetect.version + "</b>");

More methods to detect more browsers you can find in this question: Correct way to use Modernizr to detect IE?

If you want support IE 11/10/9 in your Angular app - add polyfills. For older IE version detection use code below:

function detectIE() {
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);
}

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);
}

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

// other browser
return false;
}

or

<!--[if lt IE 9]>
Place Content here for Users of Internet Explorer 9 or lower.
<![endif]-->

in HTML code.

Ok, if I'll write clean javascript code, what should i do with tag. Can I just remove it from the DOM? If i can, when it should be done? I think you have already mention, I am a newbie in Angular. — pavel, Sep 08 '17 at 15:10
Yes, you can remove tag(but then you should load this script before AngularJS code) or redirect user to static page with not-supported message, example: http://yourdomain/browser-not-supported.html (this is preffered way) — Krzysztof Raciniewski, Sep 08 '17 at 15:16
Whoa, that's a wholalot of code for simple `if (/MSIE |Trident\/|Edge\//.test(window.navigator.userAgent)) { window.location.replace("unsupported.html"); }` — Endrju, Apr 23 '20 at 06:46

score 1 · Answer 2 · answered Dec 16 '21 at 21:04

if you don't need know which browser or version, exists other way.

In index.html, check the content of app-root tag.

...
<script>
  function checkSupport() {
    var appRoot = document.getElementsByTagName('app-root')[0];
    if (appRoot && appRoot.innerHTML === '') {
      appRoot.innerHTML = '<h1>Old Browser Man!</h1> <p>Please, be smart and update it!</p>';
    }
  }
</script>

<body class="mat-typography theme" onload="checkSupport()">
  <app-root></app-root>
</body>
...

Angular 2 How to show warning page if browser is unsupported

2 Answers2