Creating accept header interception for $http in Angular

get-header-interceptor.ts

/** @ngInject */
function _getHeaderInterceptor(utils: Nebbia.IUtils) {
    const interceptor: ng.IHttpInterceptor = {
        request: (config: ng.IRequestConfig) => {
            const isGet = utils.stringContains("GET", config.method, false);
            const hasJsonAcceptType = utils.stringContains("/json", config.headers["Accept"], false);
            const isHtmlFileRequest = _isHtmlUrl();
            if (isGet && isHtmlFileRequest && hasJsonAcceptType) {
                config.headers["Accept"] = "application/html, text/html, */*";
            }
            return config;

            function _isHtmlUrl(): boolean {
                const index = config.url.lastIndexOf(".");
                if (index === -1) {
                    return false;
                }
                const fileExt = config.url.slice(index);
                const isHtml = fileExt === "html";
                return isHtml;
            }
        }
    }
}