Create a typescript + webpack 4 + tslint project

In this article I want to show you how to create a new typescript project using webpack 4 and tslint (the well known typescript linter).

I am using my favorite IDE Webstorm from Jetbrains for this project.

First Step : I create a new empty project with File → New → Project

Second Step :

npm init --yes

This command will create a package.json file where we can store our dependencies.

The initial form of this package.json file is show below :

{
"name": "Project1",
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1"
},
"keywords": [],
"author": "",
"license": "ISC"
}

Our next move is to install locally the proper dependencies, so we issue the following command at the macOS terminal command line :

npm install --save-dev webpack webpack-cli webpack-dev-server typescript ts-loader tslint tslint-webpack-plugin

Now we have installed tslint but we must initialise it using a configuration file, so we type :

tslint --init

The result of the above action is a tslint.json file of this type :

{
"defaultSeverity": "error",
"extends": [
"tslint:recommended"
],
"jsRules": {},
"rules": {},
"rulesDirectory": []
}

We will also need a tsconfig.json file so I type the following command to the terminal line :

tsc --init

This command creates the following tsconfig.json file :

{
"compilerOptions": {
/* Basic Options */
"target": "es5", /* 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'. */
// "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. */
// "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. */
}
}

We remove the comment lines from “sourceMap”: true, line and we add the following code to this tsconfig.json file (after the compilerOptions object) :

"exclude": [
"node_modules"
]

Now it’s the perfect time to add some rules to our tslint.json file.
I add the following rules to make my typescript programming life a lot easier!

{
"defaultSeverity": "error",
"extends": [
"tslint:recommended"
],
"jsRules": {},
"rules": {
"eofline": false,
"no-trailing-whitespace": false,
"comment-format": false,
"quotemark": false,
"no-console": false,
"one-line": false,
"no-consecutive-blank-lines": false,
"curly": false
},
"rulesDirectory": []
}

We still need a webpack.config.js file to add some configuration to our webpack 4 bunlder so here it is!

const path = require('path');
const TSLintPlugin = require('tslint-webpack-plugin');

module.exports = {
entry: path.join(__dirname, '/src/app.ts'),
output: {
filename: 'app.js',
path: __dirname + 'dist'
},
module: {
rules: [
{
test: /\.tsx?$/,
loader: 'ts-loader',
exclude: /node_modules/,
},
]
},
resolve: {
extensions: [".tsx", ".ts", ".js"]
},
plugins: [
new TSLintPlugin({
files: ['./src/**/*.ts']
})
]
};

As you can see we are using a src folder for our typescript code file so create this src folder and put this app.ts file inside :

// app.ts

export class Person {
//private id: number | null = null;
//private name: string;

constructor(private name: string, private id: number | null = null) {
this.name = name;
}

//methods
public myName(): string
{
return "Person's name: " + this.name;
}

public myId(): string
{
if (this.id != null)
return "Person's id: " + this.id;
else return "Person's id is undefined";
}
}


const person1: Person = new Person('krunal');

console.log(person1.myName());

const person2: Person = new Person('Stavros', 1);

console.log(person2.myName() + '\n' + person2.myId());

We are nearly done!

Create the following index.html file in our app root directory :

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
</head>
<body>
<script src="app.js" type="text/javascript"></script>
</body>
</html>

The last step we need to perform is adding the following line in the “scripts” object inside our package.json file :

"start": "webpack-dev-server --mode development"

Now go at the terminal line and execute the following command :

npm start

Our code compiles and we get the desired result at our browser console when we access the local page we just created (http://localhost:8080)