Detect if Flash is blocked (On-Demand) in Chrome

example.js

flashAvail({ waitFor: 10000 })
    .done( function(result){ 
        if(result.flashBlocked === false){
            // do whatever you need flash for
        } else {
            // flash is installed but blocked. present messaging
            alert('Oops!', 
                'It appears that Flash is being blocked. \
                Flash is required for Grill Circle and Facebook. \
                Please enable it and refresh the page.');
        }
    })
    .fail( function(result){ 
        // flash is not installed
        alert('Oops!', 
            'Flash does not appear to be installed. \
            Flash is required for Grill Circle and Facebook. \
            Please install it and refresh the page.');
    });

swfext.js

(function(){

    /*
     * Requires jQuery >= 1.5 and swfobject
     * 
     * Options:
     *      swfUrl: the url of the swf to load. default: 'assets/flash/BlockTest.swf'
     *      waitFor: how long to poll the swf before giving up. default: 2000
     *      lookFor: the name of the method that the swf exposes. this method
     *          can return whatever it likes. default: 'returnsTrue'
     *
     *  Returns a Deferred, resolved if Flash is installed, rejected if not.
     *      If resolved, returns {
     *          flashBlocked: bool // true is flash is installed but blocked
     *          swfobj: object // the original argument swfobject returned on success
     *      }
     */
    var flashAvail = function (options){
    
        var  settings = $.extend({
                swfUrl: 'assets/flash/BlockTest.swf'        
                ,waitFor: 2000
                ,lookFor: 'returnsTrue'
            }, options)
            ,repId = 'swfextBlockTest' + (0|Math.random()*10000)
            ,repEl = document.createElement('div')
            ,dfdResult = new $.Deferred();
    
        // make a quick div to fill
        repEl.style.display = 'none';
        repEl.id = repId;
        document.body.appendChild(repEl);
    
        swfobject.embedSWF(
                settings.swfUrl
                ,repId
                ,1, 1
                ,'9.0.0'
                ,false
                ,false
                ,false
                ,{ 
                    name: repId
                    ,allowScriptAccess: "always" 
                }
                ,swfEmbedCallback);
        
        function swfEmbedCallback(e){
        
            // e = { success: bool, id: string, ref: html object element }
            
            var  fo
                ,start = +new Date()
                ,interval;
    
            if(e.success === true){
                // flash is installed/enabled, try calling generic method to test flash block
    
                // poll for the flash to be ready, but only until the waitFor limit
                interval = setInterval(function onPoll(){
                    if(e.ref && e.ref[settings.lookFor]){
                        // flash is installed, enabled, and accessible: not blocked
                        clearInterval(interval);
                        dfdResult.resolve({ flashBlocked: false, swfobj: e });
                        document.body.removeChild(e.ref);
                    } else if(+new Date() - start > settings.waitFor){
                        // flash has not responded in the allotted time, assume
                        // it's blocked, but installed
                        clearInterval(interval);
                        dfdResult.resolve({ flashBlocked: true, swfobj: e });
                        document.body.removeChild(e.ref);
                    }
                }, 100);
    
            } else {
                // swfobj was not successful, flash is probably not installed
                // this could also be triggered from a bad path?
                dfdResult.reject(e);
            }
    
        };
         
        return dfdResult;
    }
    
    return flashAvail;
});

What does the 'settings.lookFor'?

The 'settings.lookFor' represent the name of the function inside the swf (look at ExternalInterface).
The swf should be embaded with bigger size otherwise chrome will block it.