import etag from "https://deno.land/x/etag@0.1.1/mod.ts";

API

etag()

The encode method is also exposed as the default export, for convenience.

The other API methods, including encode, decode, ifMatch, and ifNoMatch, are defined as properties of the default export. Meaning it can be used as a function and also an object:

import etag from "https://deno.land/x/etag@0.1.1/mod.ts";

etag(entity, options); // encode a tag for entity

etag.encode(entity); // same as etag(entity)
// ... see below for details on other API methods

See what we did there? We only imported etag, and it makes sense to see it used functionally…. but we’re also using it as we would in a namespace (import * as etag). 🧐

encode

etag.encode(entity: string | ArrayBuffer | Uint8Array | FileInfo);

decode

etag.decode(etag: string);

ifMatch

etag.ifMatch();

Note: Also exposed as etag.match()

ifNoMatch

etag.ifNoMatch();

Note: also accessible as etag.ifNoneMatch

Examples

Encoding

Here’s a basic example of returning a Response body with a weak eTag attached:

Using it as a Response Header

return new Response(body, {
  headers: {
    "etag": etag(body),
    // ≈ etag.encode(body)
  },
});

Creating a weak tag for a Blob

const svg = new Blob(['<svg xmlns="http://www.w3.org/2000/svg" />']);

etag(svg, false);
// ≈ etag.encode(svg, { weak: false })

Decoding

Server Middleware

The factory function exported in mod.ts is a quick and easy way to add ETag support to a project running on the Oak server framework. It probably supports other frameworks as well, but I haven’t had the chance to investigate that yet.

app.use("/:img.png", etag.factory);

How’s it work? The factory function returns a closure which receives the application context object, giving it the ability to intercept and modify headers on every request/response.

Register the factory as a middleware with your framework, define a specific URL pattern for it to be triggered on, and a deterministic ETag will be generated and injected into the response headers for all requests that match its registered pattern.

Contributing

⚠️ Fixing a bug? Create an Issue first!

Unless, of course, you’re fixing a bug for which an issue already exists!

This allows the issue to be connected to your Pull Request, creating a permanent record of your contribution to the project. It also makes it easier for maintainers to track project progression.

Creating an issue also ensures you’re given proper credit for fixing the bug.

This section assumes you have the GitHub CLI. You definitely should have it.

Fork and clone the repository locally

gh repo fork deno911/etag --clone

Create a new branch for your changes

git checkout -b fix/typo-in-readme

Make small changes and concise commits

# hack hack hack...

git commit README.md -m "fix: typos in README.md" && git push

Note: keep the scope of your changes relevant and concise.

Open a Pull Request

gh pr create --title "fix: typos in README.md"

Or just open your repo on GitHub.com and follow the prompts.

Warning: make sure you select the upstream repo for your PR!