Modules

Create Module (export)

Here we are creating a module with one exported class (meaning it can be used in another JS file).

Save this code into 'my-number.js'

//my-number.js
//module

class MyNumber {
	
	constructor(aNumber) {
		this.n = aNumber;
	}
	
	square() {
		return this.n * this.n;
	}
	
	cube() {
		return this.square() * this.n;
	}
	
	toString() {
		return `MyNumber(${this.n})`;
	}
	
}

//------------------------------------------
exports.MyNumber = MyNumber;

Use Module (import)

Import module using "require" keyword
Use class "MyNumber"

Save this code into "module-user1.js".

//module-user1.js

const
	tools = 1require('./my-number'),
	prn = (o) => console.log(o.toString());
	
let myNum = new 2tools.MyNumber(3);

prn(myNum);
prn("Square: " + myNum.square());
prn("Cube: " + myNum.cube());

Run

Run the program normally

>node module-user1
MyNumber(3)
Square: 9
Cube: 27

Create Module (export)

Here we are creating a module with two exported functions (meaning they can be used in another JS file).

Save this code into 'tools.js'.

//tools.js

const capitalize = (string) => {
	//Capitalized and return param.
	return string.charAt(0).toUpperCase() + string.slice(1);
}

const camelCaseToLabel = (camelCaseString) => {
	//'bestOperaSong' = 'Best Opera Song'
	const str = capitalize(camelCaseString);
	return str.replace(/([a-z])([A-Z])/g, '$1 $2');
}

//------------------------------------------
exports.capitalize = capitalize;
exports.camelCaseToLabel = camelCaseToLabel;

Use Module (import)

Import module using "require" keyword
Use function "capitalize" from module
Use function "camelCaseToLabel" from module

Save this code into "module-user2.js".

//module-user2.js

//"." for current (this) directory
const tools = 1require('./tools');

const name = 'asha';
console.log(`name: ${name}`);
console.log(`name (capitalized): ${2tools.capitalize(name)}`);

const varName = 'bestOperaSong';
console.log(`\nName: ${varName}`);
console.log(`Label: ${3tools.camelCaseToLabel(varName)}`);

Run

Run the program normally

>node module-user2
name: asha
name (capitalized): Asha
Name: bestOperaSong
Label: Best Opera Song