JavaScript function doesn't return correct value

Question

I'm developing a function in which I'd like to check which useragent is currently being used.
The following code is just a prototype and it returns whatever value it reads first - in this case IE.

detectDevice = function () {
    var userAgent = {
        detect: function () {
            return navigator.userAgent;
        },
        detectBrowser: function () {
            var browser = userAgent.detect();
            var currentBrowser;
            return currentBrowser = browser.indexOf('IE') ? "Internet Explore" : browser.indexOf('Mozilla') ? "FireFox" : "UserAgent not recognized!";
        },
        version: function (identifier) {
        }
    };

    alert(userAgent.detectBrowser());
}

I can't tell what's wrong. Maybe you guys can see it and tell me where I made a wrong turn.

Have you already tried to use $.browser instead? or it's not suitable for your purposes? — Fabrizio Calderan
– Fabrizio Calderan, Commented Dec 28, 2011 at 9:34
What is the problem with the code above? Also, you might be interested in api.jquery.com/jQuery.browser - you could look at the jQuery source code to see how they do it. — Douglas
– Douglas, Commented Dec 28, 2011 at 9:37
This question is similar to: How check if a string is substring with indexof [JAVASCRIPT]. If you believe it’s different, please edit the question, make it clear how it’s different and/or how the answers on that question are not helpful for your problem. — dumbass
– dumbass, Commented Oct 17 at 8:12

Rob W · Accepted Answer · 2011-12-28 09:36:40Z

6

indexOf returns -1 if no match is found. If a match is found, the returned value is the character index of the found substring.

To check whether a substring exists, you should use:

browser.indexOf('IE') != -1
// If a match is found, a non-negative index is returned. So, this also works:
//..... indexOf('IE') > -1
// .... indexOf('IE') >= 0

answered Dec 28, 2011 at 9:36

Rob W

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Fabrizio Calderan · Accepted Answer · 2011-12-28 09:38:26Z

2

return (browser.indexOf('IE') > -1)
           ? "Internet Explorer" 
           : (browser.indexOf('Mozilla') > -1)
                ? "FireFox" 
                : "UserAgent not recognized!";

answered Dec 28, 2011 at 9:38

Fabrizio Calderan

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1 Comment

Douglas Over a year ago

I'm not going to upvote this answer, since despite being correct, it doesn't describe why it works.

Murtaza · Accepted Answer · 2011-12-28 09:49:02Z

0

You are not checking the value of the index...

if you find the indexOf('IE') >= 0 hould be your line...

answered Dec 28, 2011 at 9:49

Murtaza

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