How to use the modernizr.fullscreen function in modernizr

static checkBrowserFunctionalities(state, action) {
        // Here we check for any missing browser functionalities that we
        // want to alert the user about. Note, Modernizr checks are used elsewhere
        // but those are not intended to inform the user that functionality is missing
        let alerts = state.get("alerts");
        if (!Modernizr.fullscreen) {
            alerts = alerts.push(
                alert.merge({
                    title: appStrings.ALERTS.BROWSER_FUNCTIONALITY_MISSING.title,
                    body: appStrings.ALERTS.BROWSER_FUNCTIONALITY_MISSING.formatString
                        .replace("{FUNCTIONALITY}", "Fullscreen")
                        .replace(
                            "{SYMPTOM}",
                            "This application will not be able to enter fullscreen mode"
                        ),
                    severity: 2,
                    time: new Date()
                })
            );
        }
        if (!Modernizr.webgl) {
            alerts = alerts.push(