coep-middleware



HTTP cross-origin embedder policy(COEP) middleware.

Compliant with
HTML Living Standard, 7.1.4 Cross-origin embedder policies.

Middleware

For a definition of Universal HTTP middleware, see the
http-middleware project.

Usage

Middleware adds the Cross-Origin-Embedder-Policy header to the response.

``ts
import {
coep,
type Handler,
} from "https://deno.land/x/coep_middleware@$VERSION/mod.ts";
import { assert } from "https://deno.land/std/testing/asserts.ts";

declare const request: Request;
declare const handler: Handler;

const middleware = coep();
const response = await middleware(request, handler);

assert(response.headers.has("cross-origin-embedder-policy"));
`

yield:

`http
Cross-Origin-Embedder-Policy: require-corp
`

Options

The middleware factory accepts the following fields:

| Name | Type | Default | Description |
| ---------- | --------------------------------------------------------------- | :--------------: | ------------------------------------- |
| policy | "require-corp" | "unsafe-none" | credentialless | "require-corp" | Embedder policy value. |
| reportTo | string | - | Reporting endpoint name. |
| reportOnly | boolean | false | Whether header is report-only or not. |

$3

If specified, change the
embedder policy value.

`ts
import { coep } from "https://deno.land/x/coep_middleware@$VERSION/middleware.ts";

const middleware = coep({ policy: "credentialless" });
`

yield:

`http
Cross-Origin-Embedder-Policy: credentialless
`

$3

If specified, adds a report-to param to the output.

`ts
import { coep } from "https://deno.land/x/coep_middleware@$VERSION/middleware.ts";

const middleware = coep({ reportTo: "default" });
`

yield:

`http
Cross-Origin-Embedder-Policy: require-corp;report-to=default
`

$3

Depending on the value, the header will be:

| Value | Field name |
| ------- | ------------------------------------------ |
| true | Cross-Origin-Embedder-Policy-Report-Only |
| false | Cross-Origin-Embedder-Policy |

`ts
import { coep } from "https://deno.land/x/coep_middleware@$VERSION/middleware.ts";

const middleware = coep({ reportOnly: true });
`

yield:

`http
Cross-Origin-Embedder-Policy-Report-Only: require-corp
`

$3

If serialize of embedder policy fails, it may throw TypeError.

Serialize fails in the following cases:

- If reportTo field is an invalid

syntax

`ts
import { coep } from "https://deno.land/x/coep_middleware@$VERSION/middleware.ts";
import { assertThrows } from "https://deno.land/std/testing/asserts.ts";

assertThrows(() => coep({ reportTo: "" }));
`

Conditions

Middleware will execute if all of the following conditions are met:

- Response does not include Cross-Origin-Embedder-Policy header
- Response does not include Cross-Origin-Embedder-Policy-Report-Only` header

Effects

Middleware may make changes to the following elements of the HTTP message.

- HTTP Headers
- Cross-Origin-Embedder-Policy
- Cross-Origin-Embedder-Policy-Report-Only

API

All APIs can be found in the
deno doc.

License

Copyright © 2023-present httpland.

Released under the MIT license