@httpland/coop-middleware/esm/middleware.js

HTTP cross-origin opener policy(COOP) middleware

// Copyright 2023-latest the httpland authors. All rights reserved. MIT license.
// This module is browser compatible.
import { CrossOriginOpenerPolicyValue, PolicyHeader } from "./constants.js";
import { withHeader } from "./deps.js";
import { stringifyCrossOriginOpenerPolicy } from "./utils.js";
/** Create cross-origin opener policy middleware.
 *
 * @example
 * ```ts
 * import {
 *   coop,
 *   type Handler,
 * } from "https://deno.land/x/coop_middleware@$VERSION/mod.ts";
 * import { assert } from "https://deno.land/std/testing/asserts.ts";
 *
 * declare const request: Request;
 * declare const handler: Handler;
 *
 * const middleware = coop();
 * const response = await middleware(request, handler);
 *
 * assert(response.headers.has("cross-origin-opener-policy"));
 * ```
 */
export function coop(options) {
    const { policy: value = CrossOriginOpenerPolicyValue.SameOrigin, reportOnly, reportTo, } = options ?? {};
    const fieldValue = stringifyCrossOriginOpenerPolicy({ value, reportTo });
    const fieldName = reportOnly
        ? PolicyHeader.CrossOriginOpenerPolicyReportOnly
        : PolicyHeader.CrossOriginOpenerPolicy;
    return async (request, next) => {
        const response = await next(request);
        if (response.headers.has(fieldName))
            return response;
        return withHeader(response, fieldName, fieldValue);
    };
}