@httpland/nel-middleware/script/middleware.js

HTTP network error logging(NEL) middleware

"use strict";
// Copyright 2023-latest the httpland authors. All rights reserved. MIT license.
// This module is browser compatible.
Object.defineProperty(exports, "__esModule", { value: true });
exports.nel = void 0;
const deps_js_1 = require("./deps.js");
const utils_js_1 = require("./utils.js");
const constants_js_1 = require("./constants.js");
/** Create `NEL` header field middleware.
 *
 * @example
 * ```ts
 * import {
 *   type Handler,
 *   nel,
 * } from "https://deno.land/x/nel_middleware@$VERSION/mod.ts";
 * import { assert } from "https://deno.land/std/testing/asserts.ts";
 *
 * declare const request: Request;
 * declare const handler: Handler;
 *
 * const middleware = nel({ report_to: "default", max_age: 86400 });
 * const response = await middleware(request, handler);
 *
 * assert(response.headers.has("nel"));
 * ```
 *
 * @throws {Error} If the endpoints include invalid member.
 */
function nel(policy) {
    (0, utils_js_1.assertValidNELPolicy)(policy);
    const fieldValue = (0, deps_js_1.stringifyJfv)([policy]);
    return async (request, next) => {
        const response = await next(request);
        if (response.headers.has(constants_js_1.Header.NEL))
            return response;
        return (0, deps_js_1.withHeader)(response, constants_js_1.Header.NEL, fieldValue);
    };
}
exports.nel = nel;