Some snippets that show how some open source projects first started out

vectorious-origin.js

/*
 * Initial steps of the mateogianolio/vectorious library
 * https://github.com/mateogianolio/gravity/blob/master/js/vector.js
 */

function Vector(x, y) {
	this.x = x;
	this.y = y;
}

// Addition
Vector.prototype.add = function(vector) {
	return new Vector(this.x + vector.x, this.y + vector.y);
};
	
// Subtraction
Vector.prototype.subtract = function(vector) {
	return new Vector(this.x - vector.x, this.y - vector.y);
};
	
// Dot product
Vector.prototype.dot = function(vector) {
	return (this.x * vector.x + this.y * vector.y);
}
	
// Scaling
Vector.prototype.scale = function(c) {
	return new Vector(this.x * c, this.y * c);
}
	
// Calculation of magnitude
Vector.prototype.magnitude = function() {
	return Math.sqrt(this.x * this.x + this.y * this.y);
}
	
// Calculation of unit vector
Vector.prototype.unitvector = function() {
	var mag = this.magnitude();
	if(mag != 0)
		return new Vector(this.x / mag, this.y / mag);
		
	return new Vector(0, 0);
}