vector_type.js

'use strict'
class Vec {
	constructor(x = 0, y = 0) {
		this.x = x
		this.y = y
	}

	plus(other) {
		return new Vec(this.x + other.x, this.y + other.y);		
	}

	minus(other) {
		return new Vec(this.x - other.x, this.y - other.y);		
	}

	get length() {
		return Math.sqrt(this.x * this.x + this.y * this.y);
	}
}

console.log(new Vec(1, 2).plus(new Vec(2, 3)));
// → Vec{x: 3, y: 5}
console.log(new Vec(1, 2).minus(new Vec(2, 3)));
// → Vec{x: -1, y: -1}
console.log(new Vec(3, 4).length);
// → 5