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Setup Node/Express with TypeScript

Hello All,

In this blog we are going to learn how to setup Node/Express with TypeScript for awesome backend development workflow with good folder structure as bonus.

Dependencies Installation

You should have Node.js installed in your dev machine.(Why wouldn't you?)
We will install other dependencies when it will be required.

Firstly, we need to initialize npm project

 npm init -y

Secondly, we need Express and Cors as our production dependency

 npm i express cors

Now since we have the basic setup ready let's start main part for which you are reading this blog!

We need to install typescript, nodemon(for restart on save), ts-node(to run typescript file using node compiler) package.

 npm i -D typescript nodemon ts-node

Folder Structure

For reference please visit one of my project on Github

We need to create src folder which will contain whole codebase(just like react)

build Directory will be generated by TypeScript(Reference at bottom of this blog).

*You can also create types folder containing all interface and types of the project.

TypeScript Configuration

We need to setup TypeScript Configuration to build application for production use.(as typescript will not be needed in production)

tsc --init

This command will generate a tsconfig.json file, with all default typescript configuration.

We just need to edit our rootDir and outDir in compilerOptions

  "compilerOptions": {
    /* Visit to read more about this file */

    /* Basic Options */
    // "incremental": true,                   /* Enable incremental compilation */
    "target": "es5",                          /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019', 'ES2020', 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', or 'react'. */
    // "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 */
    // "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. */

    /* 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. */

This will be the generated tsconfig.json file,
Uncomment rootDir and outDir and write their value like this.

 "outDir": "./build",                        /* Redirect output structure to the directory. */
 "rootDir": "./src",                       /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */ 

When Running build command(will create that later on this post), TypeScript compiler will generate compiled JavaScript in build folder code to run on server.

Installing Packages(TypeScript Way)

We always install npm packages with there type annotation while using TypeScript. Some packages contains TypeScript Annotation by default, But for most of packages we need to install @types/package-name.

You can search on npmjs to confirm if @types annotations are present or not for your desired package.

So, To Create a Simple server we need to install few packages.

 npm i -D @types/express @types/cors

Creating express server

Create a App.ts file in /src/ directory, and copy the code snippet to create a basic Hello World server.

import express, { Request, Response } from "express";
import cors from "cors";
const app = express()


app.get("/", (req: Request, res: Response) => {
  res.status(200).send("Hello World!");

  console.log('Server Started at Port, 8000')

Yes, With TypeScript we can use ES6 modules in Node.js also..

Creating npm commands

We need to create npm commands to compile or run our Project,

First, Edit package.json file and add these lines in scripts:{} object.

"scripts": {
    "devStart": "nodemon ./src/App.ts",
    "start": "node ./build/App.js",
    "build": "tsc"

devStart: Will run a Development server with reload on save using nodemon.
start: Will run Production server with build(compiled) JavaScript code.
build: Will generate compiled JavaScript code from TypeScript code.

** Remember, You must build your project before starting production server.

Running our App

Now, Everything is perfect(hopefully😅).
We are all set to run our app.

Open Terminal and type:

 npm run devStart  //To run development server(with auto reload on save)

 npm run build     //To compile TypeScript code in JavaScript

 npm start         //To run production server(with compiled JavaScript Code)

Final Talks..

Your Project Folder Structure should Look like this,
Alt Text

If everything went perfect, then your server should be running now

Comment any feedbacks please, follow me on LinkedIn

Top comments (5)

himharsh1997 profile image
Himanshu Joshi

First, you need to install typescript and tslint globally with -g option before installing them in devDependencies in your project.

tombohub profile image


himharsh1997 profile image
Himanshu Joshi

So that you can use typescript along all projects with same version and do tsc --watch to build js from it.
Actually for majority it is not a prefer way as different developer may be using different version of typescript. So you can also do npm i --save-dev typescript or install extension from code editor.

ajeelahmed1998 profile image
Ajeel Ahmed

Why did you install cors?

aryanshmahato profile image

To enable cross origin requests

Read about it here: