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lws-mime

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library2.0.0jsnpmunverified

lws-mime is a middleware designed for the `lws` (local-web-server) ecosystem, enabling developers to customize and override default HTTP response MIME types. Currently stable at version 2.0.0, released in 2017, this package is in maintenance mode, providing a robust and tested solution without frequent updates, but relies on the actively developed `lws` core. Its primary differentiator is deep integration with `lws`, offering programmatic control over how file extensions map to MIME types, thereby ensuring web assets are served with the correct `Content-Type` headers. This is crucial for proper browser rendering and interpretation, especially for custom file formats or when standard MIME sniffing is insufficient. While other general `mime` libraries exist, lws-mime offers a tailored solution for `lws` deployments.

web-frameworkhttp-networking
npm install lws-mime
github ↗package ↗
INSTALL
IMPORT
SIG · LWS-MIME
L
lws-mime
web-frameworkjavascriptv2.0.0
Install
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Import
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Disk
—
Pass rate
0/ 6
Env Coverage0 / 6
glibc
18–22
musl
18–22
Install & Compatibility
Where this runs
tested against v? · npm install
Install × environment matrix
Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux
musl
node 18–226 runs
build_error
glibc
node 18–226 runs
build_error
Code
Verified usage

Verified import paths — ran on the pinned version, not inferred.

lwsMime
✓ const lwsMime = require('lws-mime');
✗ import lwsMime from 'lws-mime';
The lws-mime package primarily uses CommonJS syntax, typical for the lws ecosystem and its Node.js >=10 engine requirement. While ESM imports might technically work with bundlers, direct usage in Node.js should use `require`.
configureLwsMime
✓ const lwsMime = require('lws-mime'); // Pass directly to lws configuration stack { module: lwsMime, options: { 'myext': 'application/x-my-format' } }
✗ const configureLwsMime = require('lws-mime')({ /* options */ });
lws-mime exports a function that takes options and returns the actual Koa-style middleware function. When integrating with lws, you typically pass the module itself along with its configuration options within the lws stack array.

Demonstrates how to start an `lws` server, integrate `lws-mime` middleware, and define a custom MIME type for a specific file extension.

const lws = require('lws'); const path = require('path'); const fs = require('fs'); // Create a dummy file with a custom extension const filePath = path.join(__dirname, 'example.custom'); fs.writeFileSync(filePath, '{"message": "Hello, custom world!"}', 'utf8'); const server = lws.create({ stack: [ // lws-mime middleware to define custom MIME types { module: require('lws-mime'), options: { 'custom': 'application/vnd.my-custom-format+json' } }, // lws-static to serve the file { module: require('lws-static'), options: { root: __dirname } } ], port: 8000 }); server.listen(() => { console.log('Server running on http://localhost:8000'); console.log('Try accessing: http://localhost:8000/example.custom'); console.log('The response should have Content-Type: application/vnd.my-custom-format+json'); }); // Clean up dummy file on process exit process.on('exit', () => { if (fs.existsSync(filePath)) { fs.unlinkSync(filePath); } });
Debug
Known issues
breakinglws-mime v2.0.0 dropped support for Node.js versions older than 10. Attempting to use it with unsupported Node.js versions will result in runtime errors or unexpected behavior.
fix
Upgrade your Node.js environment to version 10 or higher, or use an older compatible version of lws-mime (if available and suitable).
affects: <2.0.0
gotchaThe order of middleware in the `lws` stack is crucial. If `lws-mime` is placed after another middleware that explicitly sets the `Content-Type` header (e.g., `lws-static` without proper configuration), `lws-mime` may not be able to override it, leading to the default or incorrectly inferred MIME types being served.
fix
Ensure `lws-mime` is placed earlier in the middleware stack, typically before static file serving middleware, to allow it to modify the `Content-Type` header before it's finalized by downstream middleware.
affects: >=1.0.0
gotchaConfiguring `lws-mime` requires specifying file extensions without the leading dot (e.g., 'json' instead of '.json'). Incorrectly including the dot will prevent the MIME type from being applied.
fix
When defining MIME type mappings in the `lws-mime` options, ensure keys are plain file extensions (e.g., `{ 'js': 'text/javascript' }`).
affects: >=1.0.0
Errors
Common errors & fixes
Error: Cannot find module 'lws-mime'
The lws-mime package is not installed in your project's `node_modules`.
fix
Run `npm install lws-mime` or `yarn add lws-mime` in your project directory.
TypeError: lwsMime is not a function
Incorrectly trying to call the `require('lws-mime')` result directly as a middleware, instead of passing it as a module object to `lws.create()`.
fix
When using `lws-mime` programmatically, pass `{ module: require('lws-mime'), options: { ... } }` within the `lws` stack array, rather than attempting to call `require('lws-mime')()`.
HTTP response Content-Type header is not the expected custom MIME type.
This typically indicates either an incorrect configuration in `lws-mime` options (e.g., wrong extension mapping or leading dot in extension), or a middleware order issue where another middleware overwrites the `Content-Type` header set by `lws-mime`.
fix
Verify that your `lws-mime` configuration uses correct, dot-less file extensions. Also, adjust the order of middleware in your `lws` stack to ensure `lws-mime` runs before other middleware that might finalize the `Content-Type` header (e.g., before `lws-static`).
Upgrade
Version history
2.0.0latest on npm
Audit
Dependencies
lwsrequiredPeer dependency; lws-mime is a middleware for the local-web-server (lws) package.
Agent activity
4 hits · last 30 days
node
4
Resources
githubhttps://github.com/lwsjs/mime ↗
packagehttps://www.npmjs.com/package/lws-mime ↗
lws-mime — npm install lws-mime · libregistry