NodeJs and Express with Typescript for Beginners. Easy Steps.
Tags: node, typescript, express, es6
Published: 2020-08-27 04:19:22

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
![Let's dive in](https://media1.giphy.com/media/iMBEgyXkFBtdCFS93i/giphy.gif?cid=ecf05e479m1p1vp8jlq63yjc1ps625w6s1djkl711n4q63ve&rid=giphy.gif)

> ###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
![Finally] (https://media0.giphy.com/media/ZcKASxMYMKA9SQnhIl/200.webp?cid=ecf05e47kabnkif8xer3tz9pryeo7motmul4y814pv8ajuj0&rid=200.webp)

* 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.

![Claps] (https://media2.giphy.com/media/l3q2XhfQ8oCkm1Ts4/200.webp?cid=ecf05e470buip0ia91zejwxgfv8iatoa9j0bi2ott6h9xdq7&rid=200.webp)
![Thank You] (https://media3.giphy.com/media/xUPOqFfyBzvODVNTNu/200w.webp?cid=ecf05e4763lyo81p1i95nmtw9qsf97i2ma6wkoncj0rpi5td&rid=200w.webp)

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