JavaScript: Get Angle By Two Vectors On Coordinate Plan

gistfile1.js

/**
 * Defines an x,y coordinate
 * @param {float} x coordinate
 * @param {float} y coordinate
 */
function Point (x, y) {
	this.x = x;
	this.y = y;
}

/**
 * Get angle by two vectors on a coordinate plan
 * This works regardless of origin
 * @param {Point} P2         x, y 
 * @param {Point} P1         x, y --This can be thought of as the new origin point
 * @param {bool} UseRadians [The default is degrees, however to return radians pass in true]
 */
function AngleByVectors (P1, P2, UseRadians) {
	var DeltaY = P2.y - P1.y,
		DeltaX = P2.x - P1.x;
	return !UseRadians ? Math.atan2(DeltaY, DeltaX) * 180/Math.PI : Math.atan2(DeltaY, DeltaX);
}