lws-conditional-get middleware

3.0.0 verified Thu Apr 23 auth: no javascript

lws-conditional-get is a specialized middleware designed for integration with the `lws` (local-web-server) ecosystem. Its core function is to add robust HTTP Conditional-GET caching capabilities to `lws`-powered web servers, leveraging the well-regarded `koa-conditional-get` library internally. This enables efficient resource delivery by utilizing `If-None-Match` and `If-Modified-Since` HTTP headers, thereby reducing redundant data transfers and improving client-side performance. The package is currently at version 3.0.0 and appears to be actively maintained, with a likely release cadence tied to updates in its upstream dependencies or the `lws` project itself. Its primary value lies in offering a low-configuration solution for implementing standard HTTP caching directly within the `lws` environment, abstracting away the complexities of conditional request handling.

Common errors

error Error: Cannot find module 'lws' or 'lws-conditional-get' ↓

cause The required `lws` or `lws-conditional-get` package has not been installed, or the Node.js module resolution path is incorrect.

fix

Run npm install lws lws-conditional-get in your project directory to ensure all dependencies are present.

error TypeError: conditionalGet is not a function ↓

cause This error typically occurs if you're attempting to import `lws-conditional-get` using named imports (e.g., `import { conditionalGet } from 'lws-conditional-get'`) when the package exports a default function.

fix

Use a default import for ESM (import conditionalGet from 'lws-conditional-get') or directly require the module for CommonJS (const conditionalGet = require('lws-conditional-get')).

Warnings

gotcha While `lws-conditional-get` is enabled by default if included in the `lws` stack, its behavior can be explicitly disabled via the `--no-conditional-get` command-line flag or equivalent configuration, which developers might overlook if expecting direct control. ↓

fix If unexpected caching occurs, ensure the `--no-conditional-get` flag is not present. For explicit control, you might need to manage the middleware's inclusion in the `lws` stack programmatically.

gotcha `lws-conditional-get` relies on `koa-conditional-get`. Issues or breaking changes in specific versions of `koa-conditional-get` could indirectly affect the behavior or stability of this middleware. Always check for upstream dependency release notes. ↓

fix If experiencing unexpected behavior, consult the release notes and issue trackers for both `lws-conditional-get` and `koa-conditional-get` for any known incompatibilities or required updates.

breaking Upgrading `lws` itself to a new major version might introduce changes to its middleware API, potentially requiring updates to how `lws-conditional-get` is integrated or configured, even if `lws-conditional-get` itself hasn't had a major release. ↓

fix Always review the release notes for major `lws` versions and update your `lws` configuration and middleware instantiation patterns accordingly.

Install

npm install lws-conditional-get

yarn add lws-conditional-get

pnpm add lws-conditional-get

Imports

conditionalGet

wrong

import { conditionalGet } from 'lws-conditional-get'

correct

import conditionalGet from 'lws-conditional-get'

The package exports a default function, not a named export. ESM usage.

conditionalGet
```
const conditionalGet = require('lws-conditional-get')
```
CommonJS usage. The `lws` ecosystem traditionally used CommonJS, but newer Node.js versions support ESM.
lws-conditional-get (as part of lws stack)
```
const lws = require('lws');
lws.create({ stack: [ require('lws-conditional-get')() ] });
```
Typically, the middleware function is instantiated and passed directly to the `lws` stack configuration.

Quickstart

This quickstart demonstrates how to set up an `lws` server with `lws-conditional-get` middleware to enable HTTP Conditional-GET caching for static files.

import lws from 'lws';
import conditionalGet from 'lws-conditional-get';
import fs from 'fs';
import path from 'path';

// Ensure a 'public' directory exists for static files
const publicDir = path.join(process.cwd(), 'public');
if (!fs.existsSync(publicDir)) {
  fs.mkdirSync(publicDir);
}
// Create some dummy files to serve
fs.writeFileSync(path.join(publicDir, 'index.html'), '<h1>Hello from conditional-get!</h1>\n');
fs.writeFileSync(path.join(publicDir, 'style.css'), 'body { font-family: sans-serif; }\n');

const server = lws.create({
  port: 8000,
  stack: [
    conditionalGet(), // Include the conditional-get middleware
    lws.static({ directory: publicDir }) // Serve static files from 'public'
  ]
});

server.listen(8000, () => {
  console.log('lws-conditional-get demo server running on http://localhost:8000');
  console.log('Access http://localhost:8000/index.html in your browser.');
  console.log('Subsequent requests (e.g., refresh) should show ' + '"304 Not Modified" for static assets in network inspector.');
});

// To run this example:
// 1. Create a file named `server.js`
// 2. `npm install lws lws-conditional-get`
// 3. `node server.js`