\n\n
\n\n---\n\nParameters
\n\n| Parameter | Type | Description |\n| --------- | ---- | ----------------------------------------------------------------------- |\n| `next` | `T` | The next function in the chain. Its return type must be of type of `T`. |\n\n\n\n
\n\n---\n\n##### `LastChainLinkReturns
\n\nType: `T`\n\nA function that can be invoked as part of the chain.\n\n\n\n
\n\n---\n\n##### `ChainFactoryReturns
\n\nType: `T`\n\nA function that can be invoked as the final step in the chain.\n\n\n\n = (next) => () => `1-${next()}`;\nconst function2: ChainLink = (next) => () => `2-${next()}`;\n// declare the last chain function\nconst function3: LastChainLink = () => () => \"end\";\n\n// declare the chain array\nconst chain: ChainFactory = [function1, function2, function3];\n// execute the chain array\nconst result = Chain.functions(chain)();\n\nconsole.log(result); // Output: '1-2-end'\n```\n\n
\n\n---\n\nBasic usage
\n\n```ts\n// define the chain link function type\ntype ChainFunction = () => string;\n\n// declare chain link functions\nconst function1: ChainLink\n\n = (next) => (props) => {\n // edit properties\n props.someProperty = \"Edited by 1st function\";\n props.firstFunction = true;\n // call the next function in the chain\n return next(props);\n};\n\nconst function2: ChainLink = (next) => (props) => {\n props.secondFunction = true;\n\n if (props.someProperty === \"Edited by 1st function\") {\n // stop chain execution if some condition is met.\n return props;\n }\n\n // call the next function in the chain\n return next(props);\n};\n\n// declare the last chain function\nconst function3: LastChainLink = () => (props) => {\n props.thirdFunction = true;\n return props;\n};\n\n// declare the chain array\nconst chain: ChainFactory = [function1, function2, function3];\n// declare the initial state\nconst initialState: ChainFunctionProps = {\n someProperty: \"Initial value\",\n firstFunction: false,\n secondFunction: false,\n thirdFunction: false,\n};\n// execute the chain array with initial state\nconst result = Chain.functions(chain)(initialState);\n\nconsole.log(result);\n// Output: {\n// someProperty : 'Edited by 1st function',\n// firstFunction : true,\n// secondFunction : true,\n// thirdFunction : false,\n// }\n```\n\n
\n\n---\n\nAdvance usage
\n\n```ts\ntype ChainFunctionProps = {\n someProperty: string;\n firstFunction?: boolean;\n secondFunction?: boolean;\n thirdFunction?: boolean;\n};\n// define the chain link function type\ntype ChainFunction = (props: ChainFunctionProps) => ChainFunctionProps;\n\n// declare chain link functions\nconst function1: ChainLink\n\n = (next) => () => `1-${next()}`;\nconst function2: ChainLink = (next) => () => `2-${next()}`;\nconst function3: LastChainLink = () => () => true;\n\nconst chain: ChainFactory = [\n function1,\n function2,\n function3,\n];\nconst result = Chain.functions(chain)();\n\nconsole.log(result); // Outputs: '1-2-true'\n```\n\n
\n\n---\n\n`LastChainLink` with custom return type
\n\n```ts\ntype ChainFunction = () => string;\ntype LastChainFunction = () => boolean;\n\nconst function1: ChainLink\n\n;\n\nconst function1: ChainLink = (next) => async () => {\n // simulate a long task running\n await new Promise((resolve) => setTimeout(resolve, 5000));\n return `1-${next()}`;\n};\n// this function is executed once `function1` Promise get resolved.\nconst function2: ChainLink = (next) => () => `2-${next()}`;\nconst function3: LastChainLink = () => () => \"end\";\n\nconst chain: ChainFactory = [function1, function2, function3];\nconst result = Chain.functions(chain)(); // `result` is now a promise\n\nconsole.log(await result); // Outputs: '1-2-end'\n```\n\n
\n\n---\n\n`ChainLink` functions with promises
\n\n```ts\ntype ChainFunction = () => string | Promise\n\n;\ntype LastMiddleware = () => NextResponse;\ntype MiddlewareFactory = ChainFactory;\n\nconst middleware1: Middleware = (next) => async (request, event) => {\n const { nextUrl } = request;\n\n if (nextUrl === \"...\") {\n const rewriteUrl = \"...\";\n return NextResponse.rewrite(rewriteUrl);\n }\n\n return next(request, event);\n};\n\nconst middleware2: Middleware = (next) => async (request, event) => {\n const response = await next(request, event);\n\n // do something with `response` returned by the next middleware.\n // ...\n\n return response;\n};\n\n// ensures `NextResponse.next()` is called if no one stops the chain.\nconst lastMiddleware: LastChainLink = () => () =>\n NextResponse.next();\n\nconst middlewares: MiddlewareFactory = [\n middleware1,\n middleware2,\n lastMiddleware,\n];\n\nexport const config = {\n matcher: [\n /**\n * Match all request paths except for the ones starting with:\n * - api (API routes)\n * - _next/static (static files)\n * - _next/image (image optimization files)\n * - favicon.ico (favicon file)\n */\n \"/((?!api/|_next|.*\\\\..*).*)\",\n ],\n};\n\n// note that we do not execute the chain like in the previous examples since Next.js is responsible for the execution, providing `request` and `event` parameters to the `middleware` functions.\nexport default Chain.functions(middlewares);\n```\n\n
\n\n---\n\n### Development\n\n#### Install depenendencies\n\n```bash\nnpm install\n```\n\nor using `pnpm`\n\n```bash\npnpm i\n```\n\n#### Build the source code\n\nRun the following command to test and build code for distribution.\n\n```bash\npnpm build\n```\n\n#### [ESLint](https://www.npmjs.com/package/eslint)\n\nwarnings / errors check.\n\n```bash\npnpm lint\n```\n\n#### [Jest](https://npmjs.com/package/jest)\n\nRun all the defined test suites by running the following:\n\n```bash\n# Run tests and watch file changes.\npnpm test:watch\n\n# Run tests in a CI environment.\npnpm test:ci\n```\n\n- See [`package.json`](./package.json) file scripts for more info.\n\nRun tests with coverage.\n\nAn HTTP server is then started to serve coverage files from `./coverage` folder.\n\n⚠️ You may see a blank page the first time you run this command. Simply refresh the browser to see the updates.\n\n```bash\ntest:coverage:serve\n```\n\n---\n\n### Contributing\n\nContributions are truly welcome!\n\nPlease refer to the [Contributing Doc](./CONTRIBUTING.md) for more information on how to start contributing to this project.\n\nHelp keep this project up to date with [GitHub Sponsor][sponsor-url].\n\n[![GitHub Sponsor][sponsor-badge]][sponsor-url]\n\n---\n\n### Security\n\nIf you believe you have found a security vulnerability, we encourage you to **_responsibly disclose this and NOT open a public issue_**. We will investigate all legitimate reports. Email `security@alessiofrittoli.it` to disclose any security vulnerabilities.\n\n### Made with ☕\n\nNext.js middleware chain
\n\n```ts\n// src/middleware.ts\n\nimport { NextMiddleware, NextResponse } from \"next/server\";\nimport { Chain } from \"@alessiofrittoli/chain-functions\";\nimport type {\n ChainFactory,\n ChainLink,\n LastChainLink,\n} from \"@alessiofrittoli/chain-functions/types\";\n\ntype Middleware = ChainLink\n  \n | \n \n
| \n