RocketChat/Rocket.Chat

export const isIE11: boolean = ((): boolean => {
    const { userAgent } = window.navigator;
    const msieIdx = userAgent.indexOf('MSIE');

    if (msieIdx > 0) {
        return parseInt(userAgent.substring(msieIdx + 5, userAgent.indexOf('.', msieIdx))) === 11;
    }

    // If MSIE detection fails, check the Trident engine version
    if (navigator.userAgent.match(/Trident\/7\./)) {
        return true;
    }

    return false;
})();