扩展/自定义浏览器类型识别

Creator 3.x
#1 
export enum MobileBrowserType {
        Unknown = 0,
        MobileEdgeIOS = 1,
        MobileChromeIOS = 2
}
private static _browserType: MobileBrowserType;
static get browserType (): MobileBrowserType {
    if (this._browserType) {
        return this._browserType;
    } else {
        this._browserType = this.getMobileBrowserType();
        return this._browserType;
    }
};
private static getMobileBrowserType () {
    const ua = navigator.userAgent;
    if (ua.indexOf('EdgiOS') !== -1) {
        return MobileBrowserType.MobileEdgeIOS;
    } else if (ua.indexOf('CriOS') !== -1) {
        return MobileBrowserType.MobileChromeIOS;
    } else {
        return MobileBrowserType.Unknown;
    }
}