# big-o-performance A simple html app to demonstrate performance costs of data structures. - Clone the project - Navigate to the root of the project in a termina or command prompt - Run 'npm install' - Run 'npm start' - Go to the URL specified in the terminal or command prompt to try out the app. # This app was created from the Create React App NPM. Below are instructions from that project. Below you will find some information on how to perform common tasks. You can find the most recent version of this guide [here](https://github.com/facebookincubator/create-react-app/blob/master/template/README.md). ## Table of Contents - [Updating to New Releases](#updating-to-new-releases) - [Sending Feedback](#sending-feedback) - [Folder Structure](#folder-structure) - [Available Scripts](#available-scripts) - [npm start](#npm-start) - [npm run build](#npm-run-build) - [npm run eject](#npm-run-eject) - [Displaying Lint Output in the Editor](#displaying-lint-output-in-the-editor) - [Installing a Dependency](#installing-a-dependency) - [Importing a Component](#importing-a-component) - [Adding a Stylesheet](#adding-a-stylesheet) - [Post-Processing CSS](#post-processing-css) - [Adding Images and Fonts](#adding-images-and-fonts) - [Adding Bootstrap](#adding-bootstrap) - [Adding Flow](#adding-flow) - [Adding Custom Environment Variables](#adding-custom-environment-variables) - [Integrating with a Node Backend](#integrating-with-a-node-backend) - [Proxying API Requests in Development](#proxying-api-requests-in-development) - [Deployment](#deployment) - [Now](#now) - [Heroku](#heroku) - [Surge](#surge) - [GitHub Pages](#github-pages) - [Something Missing?](#something-missing) ## Updating to New Releases Create React App is divided into two packages: * `create-react-app` is a global command-line utility that you use to create new projects. * `react-scripts` is a development dependency in the generated projects (including this one). You almost never need to update `create-react-app` itself: it’s delegates all the setup to `react-scripts`. When you run `create-react-app`, it always creates the project with the latest version of `react-scripts` so you’ll get all the new features and improvements in newly created apps automatically. To update an existing project to a new version of `react-scripts`, [open the changelog](https://github.com/facebookincubator/create-react-app/blob/master/CHANGELOG.md), find the version you’re currently on (check `package.json` in this folder if you’re not sure), and apply the migration instructions for the newer versions. In most cases bumping the `react-scripts` version in `package.json` and running `npm install` in this folder should be enough, but it’s good to consult the [changelog](https://github.com/facebookincubator/create-react-app/blob/master/CHANGELOG.md) for potential breaking changes. We commit to keeping the breaking changes minimal so you can upgrade `react-scripts` painlessly. ## Sending Feedback We are always open to [your feedback](https://github.com/facebookincubator/create-react-app/issues). ## Folder Structure After creation, your project should look like this: ``` my-app/ README.md index.html favicon.ico node_modules/ package.json src/ App.css App.js index.css index.js logo.svg ``` For the project to build, **these files must exist with exact filenames**: * `index.html` is the page template; * `favicon.ico` is the icon you see in the browser tab; * `src/index.js` is the JavaScript entry point. You can delete or rename the other files. You may create subdirectories inside `src`. For faster rebuilds, only files inside `src` are processed by Webpack. You need to **put any JS and CSS files inside `src`**, or Webpack won’t see them. You can, however, create more top-level directories. They will not be included in the production build so you can use them for things like documentation. ## Available Scripts In the project directory, you can run: ### `npm start` Runs the app in the development mode.<br> Open [http://localhost:3000](http://localhost:3000) to view it in the browser. The page will reload if you make edits.<br> You will also see any lint errors in the console. ### `npm run build` Builds the app for production to the `build` folder.<br> It correctly bundles React in production mode and optimizes the build for the best performance. The build is minified and the filenames include the hashes.<br> Your app is ready to be deployed! ### `npm run eject` **Note: this is a one-way operation. Once you `eject`, you can’t go back!** If you aren’t satisfied with the build tool and configuration choices, you can `eject` at any time. This command will remove the single build dependency from your project. Instead, it will copy all the configuration files and the transitive dependencies (Webpack, Babel, ESLint, etc) right into your project so you have full control over them. All of the commands except `eject` will still work, but they will point to the copied scripts so you can tweak them. At this point you’re on your own. You don’t have to ever use `eject`. The curated feature set is suitable for small and middle deployments, and you shouldn’t feel obligated to use this feature. However we understand that this tool wouldn’t be useful if you couldn’t customize it when you are ready for it. ## Displaying Lint Output in the Editor >Note: this feature is available with `react-scripts@0.2.0` and higher. Some editors, including Sublime Text, Atom, and Visual Studio Code, provide plugins for ESLint. They are not required for linting. You should see the linter output right in your terminal as well as the browser console. However, if you prefer the lint results to appear right in your editor, there are some extra steps you can do. You would need to install an ESLint plugin for your editor first. >**A note for Atom `linter-eslint` users** >If you are using the Atom `linter-eslint` plugin, make sure that **Use global ESLint installation** option is checked: ><img src="http://i.imgur.com/yVNNHJM.png" width="300"> Then make sure `package.json` of your project ends with this block: ```js { // ... "eslintConfig": { "extends": "./node_modules/react-scripts/config/eslint.js" } } ``` Projects generated with `react-scripts@0.2.0` and higher should already have it. If you don’t need ESLint integration with your editor, you can safely delete those three lines from your `package.json`. Finally, you will need to install some packages *globally*: ```sh npm install -g eslint babel-eslint eslint-plugin-react eslint-plugin-import eslint-plugin-jsx-a11y eslint-plugin-flowtype ``` We recognize that this is suboptimal, but it is currently required due to the way we hide the ESLint dependency. The ESLint team is already [working on a solution to this](https://github.com/eslint/eslint/issues/3458) so this may become unnecessary in a couple of months. ## Installing a Dependency The generated project includes React and ReactDOM as dependencies. It also includes a set of scripts used by Create React App as a development dependency. You may install other dependencies (for example, React Router) with `npm`: ``` npm install --save <library-name> ``` ## Importing a Component This project setup supports ES6 modules thanks to Babel. While you can still use `require()` and `module.exports`, we encourage you to use [`import` and `export`](http://exploringjs.com/es6/ch_modules.html) instead. For example: ### `Button.js` ```js import React, { Component } from 'react'; class Button extends Component { render() { // ... } } export default Button; // Don’t forget to use export default! ``` ### `DangerButton.js` ```js import React, { Component } from 'react'; import Button from './Button'; // Import a component from another file class DangerButton extends Component { render() { return <Button color="red" />; } } export default DangerButton; ``` Be aware of the [difference between default and named exports](http://stackoverflow.com/questions/36795819/react-native-es-6-when-should-i-use-curly-braces-for-import/36796281#36796281). It is a common source of mistakes. We suggest that you stick to using default imports and exports when a module only exports a single thing (for example, a component). That’s what you get when you use `export default Button` and `import Button from './Button'`. Named exports are useful for utility modules that export several functions. A module may have at most one default export and as many named exports as you like. Learn more about ES6 modules: * [When to use the curly braces?](http://stackoverflow.com/questions/36795819/react-native-es-6-when-should-i-use-curly-braces-for-import/36796281#36796281) * [Exploring ES6: Modules](http://exploringjs.com/es6/ch_modules.html) * [Understanding ES6: Modules](https://leanpub.com/understandinges6/read#leanpub-auto-encapsulating-code-with-modules) ## Adding a Stylesheet This project setup uses [Webpack](https://webpack.github.io/) for handling all assets. Webpack offers a custom way of “extending” the concept of `import` beyond JavaScript. To express that a JavaScript file depends on a CSS file, you need to **import the CSS from the JavaScript file**: ### `Button.css` ```css .Button { padding: 20px; } ``` ### `Button.js` ```js import React, { Component } from 'react'; import './Button.css'; // Tell Webpack that Button.js uses these styles class Button extends Component { render() { // You can use them as regular CSS styles return <div className="Button" />; } } ``` **This is not required for React** but many people find this feature convenient. You can read about the benefits of this approach [here](https://medium.com/seek-ui-engineering/block-element-modifying-your-javascript-components-d7f99fcab52b). However you should be aware that this makes your code less portable to other build tools and environments than Webpack. In development, expressing dependencies this way allows your styles to be reloaded on the fly as you edit them. In production, all CSS files will be concatenated into a single minified `.css` file in the build output. If you are concerned about using Webpack-specific semantics, you can put all your CSS right into `src/index.css`. It would still be imported from `src/index.js`, but you could always remove that import if you later migrate to a different build tool. ## Post-Processing CSS This project setup minifies your CSS and adds vendor prefixes to it automatically through [Autoprefixer](https://github.com/postcss/autoprefixer) so you don’t need to worry about it. For example, this: ```css .App { display: flex; flex-direction: row; align-items: center; } ``` becomes this: ```css .App { display: -webkit-box; display: -ms-flexbox; display: flex; -webkit-box-orient: horizontal; -webkit-box-direction: normal; -ms-flex-direction: row; flex-direction: row; -webkit-box-align: center; -ms-flex-align: center; align-items: center; } ``` There is currently no support for preprocessors such as Less, or for sharing variables across CSS files. ## Adding Images and Fonts With Webpack, using static assets like images and fonts works similarly to CSS. You can **`import` an image right in a JavaScript module**. This tells Webpack to include that image in the bundle. Unlike CSS imports, importing an image or a font gives you a string value. This value is the final image path you can reference in your code. Here is an example: ```js import React from 'react'; import logo from './logo.png'; // Tell Webpack this JS file uses this image console.log(logo); // /logo.84287d09.png function Header() { // Import result is the URL of your image return <img src={logo} alt="Logo" />; } export default function Header; ``` This works in CSS too: ```css .Logo { background-image: url(./logo.png); } ``` Webpack finds all relative module references in CSS (they start with `./`) and replaces them with the final paths from the compiled bundle. If you make a typo or accidentally delete an important file, you will see a compilation error, just like when you import a non-existent JavaScript module. The final filenames in the compiled bundle are generated by Webpack from content hashes. If the file content changes in the future, Webpack will give it a different name in production so you don’t need to worry about long-term caching of assets. Please be advised that this is also a custom feature of Webpack. **It is not required for React** but many people enjoy it (and React Native uses a similar mechanism for images). However it may not be portable to some other environments, such as Node.js and Browserify. If you prefer to reference static assets in a more traditional way outside the module system, please let us know [in this issue](https://github.com/facebookincubator/create-react-app/issues/28), and we will consider support for this. ## Adding Bootstrap You don’t have to use [React Bootstrap](https://react-bootstrap.github.io) together with React but it is a popular library for integrating Bootstrap with React apps. If you need it, you can integrate it with Create React App by following these steps: Install React Bootstrap and Bootstrap from NPM. React Bootstrap does not include Bootstrap CSS so this needs to be installed as well: ``` npm install react-bootstrap --save npm install bootstrap@3 --save ``` Import Bootstrap CSS and optionally Bootstrap theme CSS in the ```src/index.js``` file: ```js import 'bootstrap/dist/css/bootstrap.css'; import 'bootstrap/dist/css/bootstrap-theme.css'; ``` Import required React Bootstrap components within ```src/App.js``` file or your custom component files: ```js import { Navbar, Jumbotron, Button } from 'react-bootstrap'; ``` Now you are ready to use the imported React Bootstrap components within your component hierarchy defined in the render method. Here is an example [`App.js`](https://gist.githubusercontent.com/gaearon/85d8c067f6af1e56277c82d19fd4da7b/raw/6158dd991b67284e9fc8d70b9d973efe87659d72/App.js) redone using React Bootstrap. ## Adding Flow Flow typing is currently [not supported out of the box](https://github.com/facebookincubator/create-react-app/issues/72) with the default `.flowconfig` generated by Flow. If you run it, you might get errors like this: ```js node_modules/fbjs/lib/Deferred.js.flow:60 60: Promise.prototype.done.apply(this._promise, arguments); ^^^^ property `done`. Property not found in 495: declare class Promise<+R> { ^ Promise. See lib: /private/tmp/flow/flowlib_34952d31/core.js:495 node_modules/fbjs/lib/shallowEqual.js.flow:29 29: return x !== 0 || 1 / (x: $FlowIssue) === 1 / (y: $FlowIssue); ^^^^^^^^^^ identifier `$FlowIssue`. Could not resolve name src/App.js:3 3: import logo from './logo.svg'; ^^^^^^^^^^^^ ./logo.svg. Required module not found src/App.js:4 4: import './App.css'; ^^^^^^^^^^^ ./App.css. Required module not found src/index.js:5 5: import './index.css'; ^^^^^^^^^^^^^ ./index.css. Required module not found ``` To fix this, change your `.flowconfig` to look like this: ```ini [libs] ./node_modules/fbjs/flow/lib [options] esproposal.class_static_fields=enable esproposal.class_instance_fields=enable module.name_mapper='^\(.*\)\.css$' -> 'react-scripts/config/flow/css' module.name_mapper='^\(.*\)\.\(jpg\|png\|gif\|eot\|otf\|webp\|svg\|ttf\|woff\|woff2\|mp4\|webm\)$' -> 'react-scripts/config/flow/file' suppress_type=$FlowIssue suppress_type=$FlowFixMe ``` Re-run flow, and you shouldn’t get any extra issues. If you later `eject`, you’ll need to replace `react-scripts` references with the `<PROJECT_ROOT>` placeholder, for example: ```ini module.name_mapper='^\(.*\)\.css$' -> '<PROJECT_ROOT>/config/flow/css' module.name_mapper='^\(.*\)\.\(jpg\|png\|gif\|eot\|otf\|webp\|svg\|ttf\|woff\|woff2\|mp4\|webm\)$' -> '<PROJECT_ROOT>/config/flow/file' ``` We will consider integrating more tightly with Flow in the future so that you don’t have to do this. ## Adding Custom Environment Variables >Note: this feature is available with `react-scripts@0.2.3` and higher. Your project can consume variables declared in your environment as if they were declared locally in your JS files. By default you will have `NODE_ENV` defined for you, and any other environment variables starting with `REACT_APP_`. These environment variables will be defined for you on `process.env`. For example, having an environment variable named `REACT_APP_SECRET_CODE` will be exposed in your JS as `process.env.REACT_APP_SECRET_CODE`, in addition to `process.env.NODE_ENV`. These environment variables can be useful for displaying information conditionally based on where the project is deployed or consuming sensitive data that lives outside of version control. First, you need to have environment variables defined, which can vary between OSes. For example, let's say you wanted to consume a secret defined in the environment inside a `<form>`: ```jsx render() { return ( <div> <small>You are running this application in <b>{process.env.NODE_ENV}</b> mode.</small> <form> <input type="hidden" defaultValue={process.env.REACT_APP_SECRET_CODE} /> </form> </div> ); } ``` The above form is looking for a variable called `REACT_APP_SECRET_CODE` from the environment. In order to consume this value, we need to have it defined in the environment: ### Windows (cmd.exe) ```cmd set REACT_APP_SECRET_CODE=abcdef&&npm start ``` (Note: the lack of whitespace is intentional.) ### Linux, OS X (Bash) ```bash REACT_APP_SECRET_CODE=abcdef npm start ``` > Note: Defining environment variables in this manner is temporary for the life of the shell session. Setting permanent environment variables is outside the scope of these docs. With our environment variable defined, we start the app and consume the values. Remember that the `NODE_ENV` variable will be set for you automatically. When you load the app in the browser and inspect the `<input>`, you will see its value set to `abcdef`, and the bold text will show the environment provided when using `npm start`: ```html <div> <small>You are running this application in <b>development</b> mode.</small> <form> <input type="hidden" value="abcdef" /> </form> </div> ``` Having access to the `NODE_ENV` is also useful for performing actions conditionally: ```js if (process.env.NODE_ENV !== 'production') { analytics.disable(); } ``` ## Integrating with a Node Backend Check out [this tutorial](https://www.fullstackreact.com/articles/using-create-react-app-with-a-server/) for instructions on integrating an app with a Node backend running on another port, and using `fetch()` to access it. You can find the companion GitHub repository [here](https://github.com/fullstackreact/food-lookup-demo). ## Proxying API Requests in Development >Note: this feature is available with `react-scripts@0.2.3` and higher. People often serve the front-end React app from the same host and port as their backend implementation. For example, a production setup might look like this after the app is deployed: ``` / - static server returns index.html with React app /todos - static server returns index.html with React app /api/todos - server handles any /api/* requests using the backend implementation ``` Such setup is **not** required. However, if you **do** have a setup like this, it is convenient to write requests like `fetch('/api/todos')` without worrying about redirecting them to another host or port during development. To tell the development server to proxy any unknown requests to your API server in development, add a `proxy` field to your `package.json`, for example: ```js "proxy": "http://localhost:4000", ``` This way, when you `fetch('/api/todos')` in development, the development server will recognize that it’s not a static asset, and will proxy your request to `http://localhost:4000/api/todos` as a fallback. Conveniently, this avoids [CORS issues](http://stackoverflow.com/questions/21854516/understanding-ajax-cors-and-security-considerations) and error messages like this in development: ``` Fetch API cannot load http://localhost:4000/api/todos. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:3000' is therefore not allowed access. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled. ``` Keep in mind that `proxy` only has effect in development (with `npm start`), and it is up to you to ensure that URLs like `/api/todos` point to the right thing in production. You don’t have to use the `/api` prefix. Any unrecognized request will be redirected to the specified `proxy`. Currently the `proxy` option only handles HTTP requests, and it won’t proxy WebSocket connections. If the `proxy` option is **not** flexible enough for you, alternatively you can: * Enable CORS on your server ([here’s how to do it for Express](http://enable-cors.org/server_expressjs.html)). * Use [environment variables](#adding-custom-environment-variables) to inject the right server host and port into your app. ## Deployment By default, Create React App produces a build assuming your app is hosted at the server root. To override this, specify the `homepage` in your `package.json`, for example: ```js "homepage": "http://mywebsite.com/relativepath", ``` This will let Create React App correctly infer the root path to use in the generated HTML file. ### Now See [this example](https://github.com/xkawi/create-react-app-now) for a zero-configuration single-command deployment with [now](https://zeit.co/now). ### Heroku Use the [Heroku Buildpack for Create React App](https://github.com/mars/create-react-app-buildpack). You can find instructions in [Deploying React with Zero Configuration](https://blog.heroku.com/deploying-react-with-zero-configuration). ### Surge Install the Surge CLI if you haven't already by running `npm install -g surge`. Run the `surge` command and log in you or create a new account. You just need to specify the *build* folder and your custom domain, and you are done. ```sh email: email@domain.com password: ******** project path: /path/to/project/build size: 7 files, 1.8 MB domain: create-react-app.surge.sh upload: [====================] 100%, eta: 0.0s propagate on CDN: [====================] 100% plan: Free users: email@domain.com IP Address: X.X.X.X Success! Project is published and running at create-react-app.surge.sh ``` Note that in order to support routers that use html5 `pushState` API, you may want to rename the `index.html` in your build folder to `200.html` before deploying to Surge. This [ensures that every URL falls back to that file](https://surge.sh/help/adding-a-200-page-for-client-side-routing). ### GitHub Pages >Note: this feature is available with `react-scripts@0.2.0` and higher. Open your `package.json` and add a `homepage` field: ```js "homepage": "http://myusername.github.io/my-app", ``` **The above step is important!** Create React App uses the `homepage` field to determine the root URL in the built HTML file. Now, whenever you run `npm run build`, you will see a cheat sheet with a sequence of commands to deploy to GitHub pages: ```sh git commit -am "Save local changes" git checkout -B gh-pages git add -f build git commit -am "Rebuild website" git filter-branch -f --prune-empty --subdirectory-filter build git push -f origin gh-pages git checkout - ``` You may copy and paste them, or put them into a custom shell script. You may also customize them for another hosting provider. Note that GitHub Pages doesn't support routers that use the HTML5 `pushState` history API under the hood (for example, React Router using `browserHistory`). This is because when there is a fresh page load for a url like `http://user.github.io/todomvc/todos/42`, where `/todos/42` is a frontend route, the GitHub Pages server returns 404 because it knows nothing of `/todos/42`. If you want to add a router to a project hosted on GitHub Pages, here are a couple of solutions: * You could switch from using HTML5 history API to routing with hashes. If you use React Router, you can switch to `hashHistory` for this effect, but the URL will be longer and more verbose (for example, `http://user.github.io/todomvc/#/todos/42?_k=yknaj`). [Read more](https://github.com/reactjs/react-router/blob/master/docs/guides/Histories.md#histories) about different history implementations in React Router. * Alternatively, you can use a trick to teach GitHub Pages to handle 404 by redirecting to your `index.html` page with a special redirect parameter. You would need to add a `404.html` file with the redirection code to the `build` folder before deploying your project, and you’ll need to add code handling the redirect parameter to `index.html`. You can find a detailed explanation of this technique [in this guide](https://github.com/rafrex/spa-github-pages). ## Something Missing? If you have ideas for more “How To” recipes that should be on this page, [let us know](https://github.com/facebookincubator/create-react-app/issues) or [contribute some!](https://github.com/facebookincubator/create-react-app/edit/master/template/README.md)

A Node.js module for Express that makes using a CDN for your static assets a breeze.

# Routing with EdgeJS https://github.com/Nate158s The `{{ PACKAGE_NAME }}/core` package provides a JavaScript API for controlling routing and caching from your code base rather than a CDN web portal. Using this _{{ EDGEJS_LABEL }}_ approach allows this vital routing logic to be properly tested, reviewed, and version controlled, just like the rest of your application code. Using the Router, you can: - Proxy requests to upstream sites - Send redirects from the network edge - Render responses on the server using Next.js, Nuxt.js, Angular, or any other framework that supports server side rendering. - Alter request and response headers - Send synthetic responses - Configure multiple destinations for split testing ## Configuration To define routes for {{ PRODUCT_NAME }}, create a `routes.js` file in the root of your project. You can override the default path to the router by setting the `routes` key in `{{ CONFIG_FILE }}`. The `routes.js` file should export an instance of `{{ PACKAGE_NAME }}/core/router/Router`: ```js // routes.js const { Router } = require('{{ PACKAGE_NAME }}/core/router') module.exports = new Router() ``` ## Declare Routes Declare routes using the method corresponding to the HTTP method you want to match. ```js // routes.js const { Router } = require('{{ PACKAGE_NAME }}/core/router') module.exports = new Router().get('/some-path', ({ cache, proxy }) => { // handle the request here }) ``` All HTTP methods are available: - get - put - post - patch - delete - head To match all methods, use `match`: ```js // routes.js const { Router } = require('{{ PACKAGE_NAME }}/core/router') module.exports = new Router().match('/some-path', ({ cache, proxy }) => { // handle the request here }) ``` ## Route Execution When {{ PRODUCT_NAME }} receives a request, it executes **each route that matches the request** in the order in which they are declared until one sends a response. The following methods return a response: - [appShell](/docs/api/core/classes/_router_responsewriter_.responsewriter.html#appshell) - [compute](/docs/api/core/classes/_router_responsewriter_.responsewriter.html#compute) - [proxy](/docs/api/core/classes/_router_responsewriter_.responsewriter.html#proxy) - [redirect](/docs/api/core/classes/_router_responsewriter_.responsewriter.html#redirect) - [send](/docs/api/core/classes/_router_responsewriter_.responsewriter.html#send) - [serveStatic](/docs/api/core/classes/_router_responsewriter_.responsewriter.html#servestatic) - [serviceWorker](/docs/api/core/classes/_router_responsewriter_.responsewriter.html#serviceworker) - [stream](/docs/api/core/classes/_router_responsewriter_.responsewriter.html#stream) - [use](/docs/api/core/classes/_router_responsewriter_.responsewriter.html#compute) Multiple routes can therefore be executed for a given request. A common pattern is to add caching with one route and render the response with a later one using middleware. In the following example we cache then render a response with Next.js: ```js const { Router } = require('{{ PACKAGE_NAME }}/core/router') const { nextRoutes } = require('{{ PACKAGE_NAME }}/next') // In this example a request to /products/1 will be cached by the first route, then served by the `nextRoutes` middleware new Router() .get('/products/:id', ({ cache }) => { cache({ edge: { maxAgeSeconds: 60 * 60, staleWhileRevalidateSeconds: 60 * 60 }, }) }) .use(nextRoutes) ``` ### Alter Requests and Responses {{ PRODUCT_NAME }} offers APIs to manipulate request and response headers and cookies. The APIs are: | Operation | Request | Upstream Response | Response sent to Browser | | ------------- | --------------------- | ------------------------------ | ------------------------ | | Set header | `setRequestHeader` | `setUpstreamResponseHeader` | `setResponseHeader` | | Add cookie | `*` | `addUpstreamResponseCookie` | `addResponseCookie` | | Update header | `updateRequestHeader` | `updateUpstreamResponseHeader` | `updateResponseHeader` | | Update cookie | `*` | `updateUpstreamResponseCookie` | `updateResponseCookie` | | Remove header | `removeRequestHeader` | `removeUpstreamResponseHeader` | `removeResponseHeader` | | Remove cookie | `*` | `removeUpstreamResponseCookie` | `removeResponseCookie` | `*` Adding, updating, or removing a request cookie can be achieved with `updateRequestHeader` applied to `cookie` header. You can find detailed descriptions of these APIs in the `{{ PACKAGE_NAME }}/core` [documentation](/docs/api/core/classes/_router_responsewriter_.responsewriter.html). #### Embedded Values You can inject values from the request or response into headers or cookies as template literals using the `${value}` format. For example: `setResponseHeader('original-request-path', '${path}')` would add an `original-request-path` response header whose value is the request path. | Value | Embedded value | Description | | --------------- | ---------------------- | ----------------------------------------------------------------------------------------------------------------------------- | | HTTP method | `${method}` | The value of the HTTP method used for the request (e.g. `GET`) | | URL | `${url}` | The complete URL path including any query strings (e.g. `/search?query=docs`). Protocol, hostname, and port are not included. | | Path | `${path}` | The URL path excluding any query strings (e.g. `/search`) | | Query string | `${query:<name>}` | The value of the `<name>` query string or empty if not available. | | Request header | `${req:<name>}` | The value of the `<name>` request header or empty if not available. | | Request cookie | `${req:cookie:<name>}` | The value of the `<name>` cookie in `cookie` request header or empty if not available. | | Response header | `${res:<name>}` | The value of the `<name>` response header or empty if not available. | ## Route Pattern Syntax The syntax for route paths is provided by [path-to-regexp](https://github.com/pillarjs/path-to-regexp#path-to-regexp), which is the same library used by [Express](https://expressjs.com/). ### Named Parameters Named parameters are defined by prefixing a colon to the parameter name (`:foo`). ```js new Router().get('/:foo/:bar', res => { /* ... */ }) ``` **Please note:** Parameter names must use "word characters" (`[A-Za-z0-9_]`). #### Custom Matching Parameters Parameters can have a custom regexp, which overrides the default match (`[^/]+`). For example, you can match digits or names in a path: ```js new Router().get('/icon-:foo(\\d+).png', res => { /* ... */ }) ``` **Tip:** Backslashes need to be escaped with another backslash in JavaScript strings. #### Custom Prefix and Suffix Parameters can be wrapped in `{}` to create custom prefixes or suffixes for your segment: ```js new Router().get('/:attr1?{-:attr2}?{-:attr3}?', res => { /* ... */ }) ``` ### Unnamed Parameters It is possible to write an unnamed parameter that only consists of a regexp. It works the same the named parameter, except it will be numerically indexed: ```js new Router().get('/:foo/(.*)', res => { /* ... */ }) ``` ### Modifiers Modifiers must be placed after the parameter (e.g. `/:foo?`, `/(test)?`, `/:foo(test)?`, or `{-:foo(test)}?`). #### Optional Parameters can be suffixed with a question mark (`?`) to make the parameter optional. ```js new Router().get('/:foo/:bar?', res => { /* ... */ }) ``` **Tip:** The prefix is also optional, escape the prefix `\/` to make it required. #### Zero or More Parameters can be suffixed with an asterisk (`*`) to denote zero or more parameter matches. ```js new Router().get('/:foo*', res => { /* res.params.foo will be an array */ }) ``` The captured parameter value will be provided as an array. #### One or More Parameters can be suffixed with a plus sign (`+`) to denote one or more parameter matches. ```js new Router().get('/:foo+', res => { /* res.params.foo will be an array */ }) ``` The captured parameter value will be provided as an array. ## Matching Method, Query Parameters, Cookies, and Headers Match can either take a URL path, or an object which allows you to match based on method, query parameters, cookies, or request headers: ```js router.match( { path: '/some-path', // value is route-pattern syntax method: /GET|POST/i, // value is a regular expression cookies: { currency: /^(usd)$/i }, // keys are cookie names, values are regular expressions headers: { 'x-moov-device': /^desktop$/i }, // keys are header names, values are regular expressions query: { page: /^(1|2|3)$/ }, // keys are query parameter names, values are regular expressions }, () => {}, ) ``` ## Body Matching for POST requests You can also match HTTP `POST` requests based on their request body content as in the following example: ```js router.match( { body: { parse: 'json', criteria: { operationName: 'GetProducts' } }, // the body content will parsed as JSON and the parsed JSON matched against the presence of the criteria properties (in this case a GraphQL operation named 'GetProducts') }, () => {}, ) ``` Currently the only body content supported is JSON. Body content is parsed as JSON and is matched against the presence of the fields specified in the `criteria` field. The [_POST Body Matching Criteria_](#section_post_body_matching_criteria) section below contains examples of using the `criteria` field. Body matching can be combined with other match parameters such as headers and cookies. For example, ```js router.match( { // Only matches GetProducts operations to the /graphql endpoint // for logged in users path: '/graphql', cookies: { loginStatus: /^(loggedIn)$/i }, // loggedin users body: { parse: 'json', criteria: { operationName: 'GetProducts' } }, }, () => {}, ) ``` ### Caching & POST Body Matching When body matching is combined with `cache` in a route, **the HTTP request body will automatically be used as the cache key.** For example, the code below will cache GraphQL `GetProducts` queries using the entire request body as the cache key: ```js router.match( { body: { parse: 'json', criteria: { operationName: 'GetProducts' } }, }, ({ cache }) => { cache({ edge: { maxAgeSeconds: 60 * 60, staleWhileRevalidateSeconds: 60 * 60 * 24, // this way stale items can still be prefetched }, }) }, ) ``` You can still add additional parameters to the cache key using the normal {{ EDGEJS_LABEL }} `key` property. For example, the code below will cache GraphQL `GetProducts` queries separately for each user based on their userID cookie _and_ the HTTP body of the request. ```js router.match( { body: { parse: 'json', criteria: { operationName: 'GetProducts' } }, }, ({ cache }) => { cache({ edge: { maxAgeSeconds: 60 * 60, staleWhileRevalidateSeconds: 60 * 60 * 24, // this way stale items can still be prefetched }, key: new CustomCacheKey().addCookie('userID'), // Split cache by userID }) }, ) ``` ### POST Body Matching Criteria The `criteria` property can be a string or regular expression. For example, the router below, ```js router.match( { body: { parse: 'json', criteria: { foo: 'bar' } }, }, () => {}, ) ``` would match an HTTP POST request body containing: ```js { "foo": "bar", "bar": "foo" } ``` ### Regular Expression Criteria Regular expressions can also be used as `criteria`. For example, ```js router.match( { body: { parse: 'json', criteria: { operationName: /^Get/ } }, }, () => {}, ) ``` would match an HTTP POST body containing: ```js { "operationName": "GetShops", "query": "...", "variables": {} } ``` ### Nested JSON Criteria You can also use a nested object to match a field at a specific location in the JSON. For example, ```js router.match( { body: { parse: 'json', criteria: { operation: { name: 'GetShops', }, }, }, }, () => {}, ) ``` would match an HTTP POST body containing: ```js { "operation": { "name": "GetShops", "query": "..." } } ``` ## GraphQL Queries The {{ EDGEJS_LABEL }} router provides a `graphqlOperation` method for matching GraphQL. ```js router.graphqlOperation('GetProducts', res => { /* Handle the POST for the GetProducts query specifically */ }) ``` By default, the `graphqlOperation` assumes your GraphQL endpoint is at `/graphql`. You can alter this behavior by using the `path` property as shown below: ```js router.graphqlOperation({ path: '/api/graphql', name: 'GetProducts' }, res => { /* Handle the POST for the GetProducts query specifically */ }) ``` Note that when the `graphqlOperation` function is used, the HTTP request body will automatically be included in the cache key. The `graphqlOperation` function is provided to simplify matching of common GraphQL scenarios. For complex GraphQL matching (such as authenticated data), you can use the generic [_Body Matching for POST requests_](#section_body_matching_for_post_requests) feature. See the guide on [Implementing GraphQL Routing](/guides/graphql) in your project. ## Request Handling The second argument to routes is a function that receives a `ResponseWriter` and uses it to send a response. Using `ResponseWriter` you can: - Proxy a backend configured in `{{ CONFIG_FILE }}` - Serve a static file - Send a redirect - Send a synthetic response - Cache the response at edge and in the browser - Manipulate request and response headers [See the API Docs for Response Writer](/docs/__version__/api/core/classes/_router_responsewriter_.responsewriter.html) ## Full Example This example shows typical usage of `{{ PACKAGE_NAME }}/core`, including serving a service worker, next.js routes (vanity and conventional routes), and falling back to a legacy backend. ```js // routes.js const { Router } = require('{{ PACKAGE_NAME }}/core/router') module.exports = new Router() .get('/service-worker.js', ({ serviceWorker }) => { // serve the service worker built by webpack serviceWorker('dist/service-worker.js') }) .get('/p/:productId', ({ cache }) => { // cache products for one hour at edge and using the service worker cache({ edge: { maxAgeSeconds: 60 * 60, staleWhileRevalidateSeconds: 60 * 60, }, browser: { maxAgeSeconds: 0, serviceWorkerSeconds: 60 * 60, }, }) proxy('origin') }) .fallback(({ proxy }) => { // serve all unmatched URLs from the origin backend configured in {{ CONFIG_FILE }} proxy('origin') }) ``` ## Errors Handling You can use the router's `catch` method to return specific content when the request results in an error status (For example, a 500). Using `catch`, you can also alter the `statusCode` and `response` on the edge before issuing a response to the user. ```js router.catch(number | Regexp, (routeHandler: Function)) ``` ### Examples To issue a custom error page when the origin returns a 500: ```js // routes.js const { Router } = require('{{ PACKAGE_NAME }}/core/router') module.exports = new Router() // Example route .get('/failing-route', ({ proxy }) => { proxy('broken-origin') }) // So let's assume that backend "broken-origin" returns 500, so instead // of rendering the broken-origin response we can alter that by specifing .catch .catch(500, ({ serveStatic }) => { serveStatic('static/broken-origin-500-page.html', { statusCode: 502, }) }) ``` The `.catch` method allows the edge router to render a response based on the result preceeding routes. So in the example above whenever we receive a 500 we respond with `broken-origin-500-page.html` from the application's `static` directory and change the status code to 502. - Your catch callback is provided a [ResponseWriter](/docs/api/core/classes/_router_responsewriter_.responsewriter.html) instance. You can use any ResponseWriter method except `proxy` inside `.catch`. - We highly recommend keeping `catch` routes simple. Serve responses using `serveStatic` instead of `send` to minimize the size of the edge bundle. ## Environment Edge Redirects In addition to sending redirects at the edge within the router configuration, this can also be configured at the environment level within the Layer0 Developer Console. Under _&lt;Your Environment&gt; &#8594; Configuration_, click _Edit_ to draft a new configuration. Scroll down to the _Redirects_ section:  Click _Add A Redirect_ to configure the path or host you wish to redirect to:  **Note:** you will need to activate and redeploy your site for this change to take effect.

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