2020-coding-standards-sample-es-class.js

/**
 * Sample ES6 classes
 */

/** Implement private methods using symbols*/
const _braceFood = Symbol ( 'braceFood' );

// Base class
class Being {

	constructor ( name, eyes = 2 ) {

		this.type = 'being';
		this.name = name;
		this.eyes = eyes;

		// Increment static counter
		Being.count++;

	}

	// Getter/setters
	set eats ( food ) {
		this.food = food;
	}

	get favouriteMeal () {
		return `${this.name} prefers ${this[ _braceFood ] ()}.`;
	}

	// Public methods
	sayHi () {
		return `${this.name} grunts`;
	}

	canJudgeDistance () {
		return this.eyes >= 2;
	}

	// Static getter
	static get howManyBeings () {
		return Being.count;
	}

	// Private method
	[ _braceFood ] () {
		return this.food || 'nothing';
	}

}

// Static Being properties
Being.count = 0;

// Human class - extending the base Being class
class Human extends Being {

	/** Class constructor */
	constructor ( name ) {

		// Call base constructor
		super ( name, 2 );
		
		this.type = 'human';

	}

	// Override method
	sayHi () {
		return `${super.sayHi ()} and says hi!`;
	}

	describeMyself () {
		return `${this.sayHi ()} I am a ${this.type}, and I have ${this.eyes} - I can${this.canJudgeDistance () ? '' : 'not'} judge distance.` +
			` For dinner, I prefer to eat ${this.favouriteMeal}.`;
	}

}

// Export all classes
module.exports = {
	Being,
	Human
};