NodeJs and Express with Typescript for Beginners. Easy Steps.

Node is a run-time environment that makes it possible to write server-side Javascript. It has gained a lot of widespread adoption since 2011, the actual release date. Writing server-side using Javascript can be hectic and worrisome as your codebase grows, due to the fact that Javascript language lacks strong static typing.

TypeScript is a typed (optional) super-set of JavaScript that can help with building and managing large-scale JavaScript projects. It can be thought of as JavaScript with additional features like strong static typing, compilation, object-oriented programming and ability to use interfaces.

Since, Typescript is an object-oriented language which makes the app code more consistent, clean, simple, testable and reusable. So it should better to use typescript for developing large projects.

Now let's dive in

Steps

• Install typescript globally if you don't have it. Open your terminal or command prompt.

npm install -g typescript

• Create a folder called NodeTypescript

• Open the folder with your favourite code editor. Mine is Visual studio code (VSCode)

• In your terminal or command prompt, we will dive inside the folder we created
  

cd NodeTypeScript

For those using vscode, you can use the command line in vscode, so you don't need to do the step above

• create app.ts

NB. tsc it's used to compile from typescript to javascript.

• let's set up our typescript config

tsc --init

NB

At default, the target is ES5, which is deprecated at the moment, ES5 uses var, while ES6+ uses let and const

1. change the target from es5 to es6 in tsconfig.json
2. uncomment the outDir and set it to dist. Note this is where we want our complied version to go to.
3. uncomment the rootDir and set it to dist. Note this is where our typescript files will be stored.
4. uncomment moduleResolution

Create folder scr then move the app.ts you created earlier to that folder.

tsconfig.json

{
  "compilerOptions": {
    /* Basic Options */
    // "incremental": true,                   /* Enable incremental compilation */
    "target": "es6",                          /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019' 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'. */
    // "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. */

    /* 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 */
    "forceConsistentCasingInFileNames": true  /* Disallow inconsistently-cased references to the same file. */
  }
}

• let's set up our node package.json

npm init --y

• Let's install dependencies and devDependencies

npm i express
npm i D typescript ts-node nodemon @types/node @types/express

• We will edit the scripts section, we will add start, dev and build start this will start the compile folder. dev this will start the typescript file. build this will compile the typescript files and save it to dist.

package.json

"scripts": {
    "start": "node dist/app.js",
    "dev": "nodemon src/app.ts",
    "build": "tsc -p ."
},

• Let's edit out app.ts

import express from 'express';

const app = express();

app.get('/', (req, res) => {
    res.send('hello');
});
const PORT = 3000;

app.listen(PORT, () => console.log(`Server Running on port ${PORT}`));

This will run on port 3000, to run this server. use the code below

npm run dev

NOTE: This will run the typescript files in the src folder.

• Let's add typescript types to our app.ts

import express, { Application, Request, Response, NextFunction } from 'express';

const app: Application = express();

app.get('/', (req: Request, res: Response, next: NextFunction) => {
    res.send('hello');
});
const PORT = 5000;

app.listen(PORT, () => console.log(`Server Running on port ${PORT}`));

WOOOOW.. Finally at the ending

• Let's compile by building our typescript file. run this command below in your command line.

npm run build

This will compile all the files in the src folder then dump them in the dist folder.

The last command we will run will be

npm start

This will run the files in the dist folder.

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