add-typescript-to-nodejs.md

tags
programming

Node.js Project Typescript Config

1. Uninstall jest (this is due to some weird version resolution between jest and babel when jest is installed in advanced)

   npm uninstall jest @types/jest

2. Install all dev dependencies

   npm i -D jest @types/jest @babel/core @babel/preset-env @babel/preset-typescript @types/aws-lambda @typescript-eslint/eslint-plugin @typescript-eslint/parser [email protected] babel-eslint babel-jest babel-loader eslint eslint-config-prettier typescript

3. If you need React, install additional dependencies

   npm i react react-dom
   npm i -D @types/react @types/react-dom @babel/preset-react

4. Add .babelrc

   {
       "presets": [
           [
               "@babel/preset-env",
               {
                   "targets": {
                       "node": "12"
                   }
               }
           ],
           "@babel/preset-typescript"
       ]
   }

   If you need React, add @babel/preset-react before @babel/preset-typescript.

5. Add .eslintrc.json

   {
       "extends": [
           "eslint:recommended",
           "plugin:@typescript-eslint/recommended",
           "prettier",
           "prettier/@typescript-eslint"
       ],
       "parser": "@typescript-eslint/parser",
       "env": {
           "node": true,
           "es6": true,
           "jest": true
       },
       "plugins": ["@typescript-eslint"],
       "rules": {
           "@typescript-eslint/interface-name-prefix": [2, "always"],
           "@typescript-eslint/explicit-function-return-type": 0,
           "@typescript-eslint/no-explicit-any": 0
       }
   }

6. Add tsconfig.json

   {
       "compilerOptions": {
           /* Basic Options */
           "target": "ES2017" /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017','ES2018' or 'ESNEXT'. */,
           "module": "commonjs" /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */,
           // "lib": [],                             /* Specify library files to be included in the compilation. */
           "allowJs": true /* Allow javascript files to be compiled. */,
           // "checkJs": true,                       /* Report errors in .js files. */
           // "jsx": "preserve",                     /* Specify JSX code generation: 'preserve', 'react-native', or 'react'. */
           "resolveJsonModule": true,
           // "declaration": true,                   /* Generates corresponding '.d.ts' file. */
           // "declarationMap": true,                /* Generates a sourcemap for each corresponding '.d.ts' file. */
           // "sourceMap": true,                     /* Generates corresponding '.map' file. */
           // "outFile": "./",                       /* Concatenate and emit output to single file. */
           // "outDir": "./",                        /* Redirect output structure to the directory. */
           // "rootDir": "./",                       /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
           // "composite": true,                     /* Enable project compilation */
           // "removeComments": true,                /* Do not emit comments to output. */
           "noEmit": true /* Do not emit outputs. */,
           // "importHelpers": true,                 /* Import emit helpers from 'tslib'. */
           // "downlevelIteration": true,            /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. */
           "isolatedModules": true,               /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */
   
           /* Strict Type-Checking Options */
           "strict": true /* Enable all strict type-checking options. */,
           "noImplicitAny": true /* Raise error on expressions and declarations with an implied 'any' type. */,
           "strictNullChecks": true /* Enable strict null checks. */,
           // "strictFunctionTypes": true,           /* Enable strict checking of function types. */
           // "strictBindCallApply": true,           /* Enable strict 'bind', 'call', and 'apply' methods on functions. */
           // "strictPropertyInitialization": true,  /* Enable strict checking of property initialization in classes. */
           // "noImplicitThis": true,                /* Raise error on 'this' expressions with an implied 'any' type. */
           // "alwaysStrict": true,                  /* Parse in strict mode and emit "use strict" for each source file. */
   
           /* Additional Checks */
           "noUnusedLocals": true /* Report errors on unused locals. */,
           "noUnusedParameters": true /* Report errors on unused parameters. */,
           // "noImplicitReturns": true,             /* Report error when not all code paths in function return a value. */
           // "noFallthroughCasesInSwitch": true,    /* Report errors for fallthrough cases in switch statement. */
   
           /* Module Resolution Options */
           // "moduleResolution": "node",            /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
           // "baseUrl": "./",                       /* Base directory to resolve non-absolute module names. */
           // "paths": {},                           /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
           // "rootDirs": [],                        /* List of root folders whose combined content represents the structure of the project at runtime. */
           // "typeRoots": [],                       /* List of folders to include type definitions from. */
           // "types": [],                           /* Type declaration files to be included in compilation. */
           // "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
           "esModuleInterop": true /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
           // "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */
   
           /* Source Map Options */
           // "sourceRoot": "",                      /* Specify the location where debugger should locate TypeScript files instead of source locations. */
           // "mapRoot": "",                         /* Specify the location where debugger should locate map files instead of generated locations. */
           // "inlineSourceMap": true,               /* Emit a single file with source maps instead of having a separate file. */
           // "inlineSources": true,                 /* Emit the source alongside the sourcemaps within a single file; requires '--inlineSourceMap' or '--sourceMap' to be set. */
   
           /* Experimental Options */
           // "experimentalDecorators": true,        /* Enables experimental support for ES7 decorators. */
           // "emitDecoratorMetadata": true,         /* Enables experimental support for emitting type metadata for decorators. */
       },
       "include": ["src"]
   }

7. Add babel-loader to webpack.config.js

   const path = require('path');
   const fs = require('fs');
   
   let nodeModules = {};
   
   const buildDir = path.join(__dirname, 'build');
   
   fs.readdirSync('node_modules')
       .filter(x => ['.bin'].indexOf(x) === -1)
       .forEach(mod => (nodeModules[mod] = 'commonjs ' + mod));
   
   /**
    * @type {import('webpack').Configuration}
    */
   module.exports = {
       entry: './src/index.ts',
       target: 'node',
       output: {
           path: buildDir,
           libraryTarget: 'commonjs',
           filename: `index.js`
       },
       module: {
           rules: [
               {
                   test: /\.(ts|tsx)$/,
                   exclude: /node_modules/,
                   use: ['babel-loader']
               }
           ]
       },
       resolve: {
           extensions: ['*', '.js', '.jsx', '.ts', '.tsx', '.json']
       },
       externals: ['aws-sdk'],
       devtool: 'source-map',
       plugins: []
   };

8. Add lint and typecheck scripts to package.json:

   {
   	"scripts": {
   		"lint": "eslint --ext .js,.ts,.tsx src --ignore-pattern \"**/*.spec.js\" --ignore-pattern \"**/*.spec.ts\"",
   		"typecheck": "tsc --noEmit"
   	}
   }