Microservices with Node, Express and Typescript

Setup a project

npm init

Install Typescript

npm i typescript

Setup tsconfig file

tsc --init

Make the following changes in the tsconfig file(check the uncommented lines).

{
  "compilerOptions": {
    /* Visit https://aka.ms/tsconfig.json to read more about this file */

    /* Basic Options */
    // "incremental": true,                         /* Enable incremental compilation */
      "target": "es6",                                /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019', 'ES2020', 'ES2021', or 'ESNEXT'. */
      "module": "commonjs",                           /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', 'es2020', 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', 'react', 'react-jsx' or 'react-jsxdev'. */
    // "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": "./dist",                              /* Redirect output structure to the directory. */
       "rootDir": "./src",                             /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
    // "composite": true,                           /* Enable project compilation */
    // "tsBuildInfoFile": "./",                     /* Specify file to store incremental compilation information */
    // "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. */
    // "noUncheckedIndexedAccess": true,            /* Include 'undefined' in index signature results */
    // "noImplicitOverride": true,                  /* Ensure overriding members in derived classes are marked with an 'override' modifier. */
    // "noPropertyAccessFromIndexSignature": true,  /* Require undeclared properties from index signatures to use element accesses. */

    /* 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. */
    // "allowUmdGlobalAccess": true,                /* Allow accessing UMD globals from modules. */

    /* 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. */

    /* Advanced Options */
    "skipLibCheck": true,                           /* Skip type checking of declaration files. */
    "forceConsistentCasingInFileNames": true        /* Disallow inconsistently-cased references to the same file. */
  }
}

Copy the package.json file and run npm i

1. The build script transpiles the typescript files(starting from the root level) to javascript and places it in the path mentioned in the outDir property in the tsconfig file.
2. The dev script runs the ts-node src/app.ts command to host the code on the local server and watch for the changes if you make any.
3. The start script hosts the thus transpiled javascript files placed in the dist folder in this case to the local server.

{
  "name": "ideaservice",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "start": "node dist/app.js",
    "dev": "nodemon src/app.ts",
    "build": "tsc -p ."
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "@types/body-parser": "^1.19.0",
    "@types/cors": "^2.8.10",
    "@types/express": "^4.17.12",
    "@types/node": "^15.12.4",
    "cors": "^2.8.5",
    "express": "^4.17.1",
    "node": "^16.3.0",
    "typescript": "^4.3.4"
  },
  "devDependencies": {
    "nodemon": "^2.0.7",
    "ts-node": "^10.0.0"
  }
}

app.ts

Entry point for your service

import express,{Application, Router} from 'express';
const app : Application = express();
import cors from 'cors';
const router:Router = require('../src/route/route')
const PORT : number = 3000;
app.use(express.json())
app.use(express.text());
app.use('/ideas/v1',router);
app.use(cors())


app.listen(3000,()=>{
    console.log(`Server started at port ${PORT}`)
})

route.ts

Setup your routes

import {Router} from  'express';
import service from '../service/service';
const router = Router();


export interface Idea {
    id: string
    title:string
    desc:string
}

router.get('/:id',async (req,res) =>{
    const id: string = req.params.id;
    const message: string | Object = await service.getIdeas(id); 
    res.json({message:`Get Ideas ${message}`})
})


router.delete('/:id',async (req,res) =>{
    const id: string = req.params.id; 
    const message: string | Object = await service.delIdeas(id);
    res.json({message:`Delete Ideas ${message}`})
})

router.put('/',async (req,res) =>{
    const idea:Idea = req.body;
    const message: string | Object = await service.addIdeas(idea);
    res.json({message:message})
})


router.post('/:id',async (req,res) =>{
    const updatedIdea:Idea = req.body;
    const id: string = req.params.id;
    const message:string | Object = await service.updateIdeas(id,updatedIdea);
    res.json({message:`${id} ${message}`})
})




module.exports = router;

service.ts

Write your bussiness logic here.

import {Idea} from '../route/route';

interface Service {
    getIdeas: (id:string)=> Promise<Object | string>
    delIdeas: (id:string)=> Promise<Object | string>
    addIdeas: (idea:Idea)=> Promise<Object | string>
    updateIdeas: (id:string,idea:Idea)=> Promise<Object | string>
}

const service : Service = {

    getIdeas: async (id:string)=>{
    
        return `Idea with id: ${id} found!`
    },
    
    
    delIdeas: async (id:string)=>{

        return `Idea with id:${id} deleted!`
    },
    
    
    addIdeas: async (idea:Idea)=>{

        return `Added Idea: ${Object.entries(idea)}`
    },
    
    
    updateIdeas: async (id:string, idea:Idea)=>{

        return `Updated Idea: ${Object.entries(idea)}`
    },

}

export default service;

Run the Typescript app!

npm run dev

OR

Run the transpiled javascript app!

npm run build
npm start