var listenerSync = function()

in media/js/base/mozilla-client.js [408:460]
39 lines of code
7 McCabe index (conditional complexity)

                var listenerSync = function (event) {
                    if (
                        !event.detail ||
                        !event.detail.data ||
                        event.detail.callbackID !== callbackID
                    ) {
                        return;
                    }

                    var config = event.detail.data;

                    // Clear the timeout and remove the event listener.
                    window.clearTimeout(timer);
                    document.removeEventListener(
                        'mozUITourResponse',
                        listenerSync,
                        false
                    );

                    /**
                     * Account signed-in state
                     * Assume being signed-in to Sync equals being signed in to an account.
                     */
                    details.setup = config.setup;

                    /**
                     * Browser services
                     * Device counts are only available in Fx50+, fallback 'unknown' if not detectable
                     */
                    details.browserServices.sync = {
                        setup: config.setup,
                        desktopDevices: Object.prototype.hasOwnProperty.call(
                            config,
                            'desktopDevices'
                        )
                            ? config.desktopDevices
                            : 'unknown',
                        mobileDevices: Object.prototype.hasOwnProperty.call(
                            config,
                            'mobileDevices'
                        )
                            ? config.mobileDevices
                            : 'unknown',
                        totalDevices: Object.prototype.hasOwnProperty.call(
                            config,
                            'totalDevices'
                        )
                            ? config.totalDevices
                            : 'unknown'
                    };

                    returnFxaDetails();
                };