export const isUrlAbsolute = (url: string) => {
    if (url) {
        if (url.indexOf("//") === 0) {
            return true;
        } // URL is protocol-relative (= absolute)
        if (url.indexOf("://") === -1) {
            return false;
        } // URL has no protocol (= relative)
        if (url.indexOf(".") === -1) {
            return false;
        } // URL does not contain a dot, i.e. no TLD (= relative, possibly REST)
        if (url.indexOf("/") === -1) {
            return false;
        } // URL does not contain a single slash (= relative)
        if (url.indexOf(":") > url.indexOf("/")) {
            return false;
        } // The first colon comes after the first slash (= relative)
        if (url.indexOf("://") < url.indexOf(".")) {
            return true;
        } // Protocol is defined before first dot (= absolute)
    }
    return false; // Anything else must be relative
};