forked from daren.hsu/line_push
150 lines
4.5 KiB
Markdown
150 lines
4.5 KiB
Markdown
# ♡ serve-placeholder
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> Connect/Express middleware to respond with better placeholders based on request instead of 404 page
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[![Standard JS][standard-src]][standard-href]
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[![david dm][david-src]][david-href]
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[![codecov][codecov-src]][codecov-href]
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[![circleci][circleci-src]][circleci-href]
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[![npm version][npm-v-src]][npm-v-href]
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[![npm downloads][npm-dt-src]][npm-dt-href]
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[![package phobia][packagephobia-src]][packagephobia-href]
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## Why?
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**💵 Rendering 404 errors is costly**
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- Each 404 error for assets means a new SSR request that adds extra loads to the server and increases crash chances.
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**👌 Graceful Responses**
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- Sometimes, we can send better responses alongside with 404 code instead of nothing. For example, for images, we send a fallback transparent 1x1 image.
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**🔍 SEO Friendly**
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- Don't allow indexing invalid URLs with ugly html pages.
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- Remove extra SSR loads when assets like `robots.txt` or `favicon.ico` doesn't exist.
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## Usage
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Install package:
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```bash
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npm install serve-placeholder
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```
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OR
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```bash
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yarn add serve-placeholder
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```
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Import and use middleware:
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```js
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const placeholder = require('serve-placeholder')
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// import placeholder from 'serve-placeholder'
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// [regular middleware such as serve-static]
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// Response with appreciate placeholders
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app.use(placeholder())
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//app.use(placeholder({ /* options */ }))
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// [global error handler]
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```
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## Options
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### `handlers`
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A mapping from file extensions to the handler. Extensions should start with *dot* like `.js`.
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You can disable any of the handlers by setting the value to `null`
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If the value of a handler is set to `false`, middleware will be ignored for that extension.
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### `statusCode`
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- Default: `404`
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Sets `statusCode` for all handled responses. Set to `false` to disable overriding statusCode.
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### `skipUnknown`
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- Default: `false`
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Skip middleware when no handler is defined for the current request.
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Please note that if this option is set to `true`, then `default` handler will be disabled!
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### `placeholders`
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- Type: `Object`
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A mapping from handler to placeholder. Values can be `String` or `Buffer`. You can disable any of the placeholders by setting the value to `false`.
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### `mimes`
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- Type: `Object`
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A mapping from handler to the mime type. Mime type will be set as `Content-Type` header. You can disable sending any of the mimes by setting the value to `false`.
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### `noCache`
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- Default: `true`
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Set headers to prevent accidentally caching 404 resources.
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When enabled, these headers will be sent:
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```js
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{
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'cache-control': 'no-cache, no-store, must-revalidate',
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'expires': '0',
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'pragma': 'no-cache'
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}
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```
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## Defaults
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These are [default handlers](./src/defaults.js). You can override every of them using provided options.
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Handler | Extensions | Mime type | Placeholder
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-----------|------------------------|--------------------------|-------------------
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`default` | any unknown extension | - | -
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`css` | `.css` | `text/css` | `/* style not found */`
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`html` | `.html`, `.htm` | `text/html` | `<!-- page not found -->`
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`js` | `.js` | `application/javascript` | `/* script not found */`
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`json` | `.json` | `application/json` | `{}`
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`map` | `.map` | `application/json` | [empty sourcemap v3 json]
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`plain` | `.txt`, `.text`, `.md` | `text/plain` | [empty]
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`image` | `.png`, `.jpg`, `.jpeg`, `.gif`, `.svg`, `.webp`, `.bmp`, `.ico` | `image/gif` | [transparent 1x1 image]
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## License
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MIT. Made with 💖 by [Nuxt.js](https://nuxtjs.org) team!
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<!-- Refs -->
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[standard-src]: https://flat.badgen.net/badge/code%20style/standard/green
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[standard-href]: https://standardjs.com
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[npm-v-src]: https://flat.badgen.net/npm/v/serve-placeholder/latest
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[npm-v-href]: https://npmjs.com/package/serve-placeholder
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[npm-dt-src]: https://flat.badgen.net/npm/dt/serve-placeholder
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[npm-dt-href]: https://npmjs.com/package/serve-placeholder
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[packagephobia-src]: https://flat.badgen.net/packagephobia/install/serve-placeholder
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[packagephobia-href]: https://packagephobia.now.sh/result?p=serve-placeholder
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[david-src]: https://flat.badgen.net/david/dep/nuxt/serve-placeholder
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[david-href]: https://david-dm.org/nuxt/serve-placeholder
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[codecov-src]: https://flat.badgen.net/codecov/c/github/nuxt/serve-placeholder/master
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[codecov-href]: https://codecov.io/gh/nuxt/serve-placeholder
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[circleci-src]: https://flat.badgen.net/circleci/github/nuxt/serve-placeholder/master
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[circleci-href]: https://circleci.com/gh/nuxt/serve-placeholder
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