Vector2d can be loaded through Require.js (AMD), CommonJS or using script tags.

Require.js

define(['vector2d'], function(Vector2d) { ... });

Common js

var Vector2d = require('vector2d').Vector2d;

Script tag

<script src="vector2d.js"></script>

A new Vector2d instance can be instantiated with or without the new operator:

var v1 = new Vector2d();
var v2 = Vector2d();

Initial vector values can also be passed to the constructor function as a list of x y values, or as an array:

var v1 = Vector2d(4, 5);
var v2 = Vector2d([1, 1]);

The vectors can now be manipulated and queried using method calls.

v1.subtract(v2);

// v1 == [3, 4]
// v2 == [1, 1]

Meaning, the calling vector gets set to the resultant of the operation.

Using .clone() makes a copy of the vector to ensure operations are non-destructive.

var result = v1.clone().subtract(v2);

// result == [3, 4]
// v1 == [4, 5]
// v2 == [1, 1]

All methods which accept a vector parameter can also accept a 2 value array instead.

v1.add([3, 3]);
v1.multiply([2, 2]);

Methods which return a vector can be chained together.

v1.add(v2).scale(2).rotate(0.5);