What version of IE uses window[objectName] instead of window.document[objectName]?

Question

I am trying to use a Javascript callback to a Flex application embedded in my page. Looking through some examples, I've seen this code used to get a reference to the Flex application:

// Get the reference:
function thisFlexApp(appName) {
    if(navigator.appName.indexOf ('Microsoft') != -1) {
        return window[appName];
    }
    else {
        return window.document[appName];
    }
}

// Use it:
var someVariable = thisFlexApp('NameOfFlexApp').callbackMethod();

I used that method, but using IE9 I got errors indicating the "thisFlexApp" call didn't work. Turns out that window.document[appName] worked in IE9, but window[appName] didn't. Since I don't expect my government clients to be using IE9 yet, I'm wondering what version of IE this method would actually work on? Is there another test that would be better to use instead of the one above which just assumes all versions of IE work a certain way? Thanks in advance.

Answer 1

Don't check the browser version, check the browser's capabilities. You can just check if window[appName] exists, and if it does, use it.

function thisFlexApp(appName) {
    if(window[appName]) {
        return window[appName];
    }
    else {
        return window.document[appName];
    }
}

Or even shorter:

function thisFlexApp(appName) {
    return window[appName] || window.document[appName];
}