How can I determine which version of IE a user is running in JavaScript?

Question

In some existing code there is a test to see if the user is running IE, by checking if the object Browser.Engine.trident is defined and returns true.

But how can I deter

Answer 1

As no-one seems to have said it yet:

The test is needed inside a JavaScript function so a conditional comment doesn't seem suitable.

You can easily put a conditional comment — a JScript conditional comment, not an HTML one — inside a function:

function something() {
    var IE_WIN= false;
    var IE_WIN_7PLUS= false;
    /*@cc_on
    @if (@_win32)
        IE_WIN= true;
        @if (@_jscript_version>=5.7)
            IE_WIN_7PLUS = true;
        @end
    @end @*/
    ...
}

It's more typical to do the test once at global level though, and just check the stored flags thereafter.

CCs are more reliable than sifting through the mess that the User-Agent string has become these days. String matching methods on navigator.userAgent can misidentify spoofing browsers such as Opera.

Of course capability sniffing is much better for cross-browser code where it's possible, but for some cases — usually bug fix workarounds — you do need to identify IE specifically, and CCs are probably the best way to do that today.